 M Jacotet-Navarro

N Rombaut

S Deslis

A.-S Fabiano

A.-S Rombaut

R Fabiano-Tixier

A Tourtois

F Bily

Chemat

A.-S Fabiano-Tixier

F.-X Pierre

Antoine Bily

F Chemat

Olivier Rigaud

Marc Roller

Lucile P Et Loubna

Mélanie, Bérengère, Amélie, Marion, Emmanuelle, Olivia, Maryline, Hichem, Oualid ainsi que François-Xavier Fabien

Jérôme

Emma Laurie

Alice Laura

Marjorie Mathieu

Justine Anthony

Julien

Nico Xavier

Richard

Keywords: ultrasound, microwaves, turbohydrodistillation Critical micellar concentration CMR Carcinogenic, Mutagenic, Reprotoxic

Chemat, Development of a "dry" bio-refinery for total valorization

Puisque cette thèse s'est déroulée en collaboration entre université et entreprise, j'ai eu l'occasion de rencontrer de nombreux collaborateurs, et, au-delà des relations professionnelles, de lier de réelles amitiés.

Je voudrais tout d'abord remercier l'équipe GREEN de l'Université d'Avignon : même si je n'ai pas été beaucoup avec vous au cours de cette thèse, cela m'a toujours fait plaisir de vous retrouver. Merci aux maîtres de conférences HDR Sandrine Périno, Njara Rakotomanomana et Maryline Vian, aux ingénieurs de recherche Karine Ruiz et Emmanuel Petitcolas et à tous les post-doctorants, doctorants et stagiaires que j'ai pu rencontrer pendent la thèse : Natacha, Mohammad, Jean-Thomas, Alice M., Céline, Loïc, Tamara, Ying, Dima&Dima, Aurore, Emna, Meryem, Clément, Carolinette, Léa, Vincent, Alice A., Bouthéina et Emilie. Une mention toute particulière à mes « coupines » AG et Cassandra : nous avons toutes les trois traversé cette aventure ensemble, depuis l'époque de petite stagiaire (chimiste de base) à aujourd'hui. Les souvenirs à vos côtés sont inoubliables, que ce soit nos conversations, nos fous rires, nos angoisses et pleurs… Je vous aime les filles ! J'ai également une pensée pour les « non-GREEN » avec qui j'ai aussi passé de super moments :

Cyril, Simon et Aurélia.

Je remercie également de tout coeur tous mes collègues et amis de chez Naturex avec

qui j'ai passé le plus clair de mon temps durant ce doctorat. Vous avez tous contribué de près ou de loin à l'élaboration de cette thèse, que ce soit par une aide, un conseil ou encore un sourire.

Je tiens tout d'abord à remercier de tout coeur le service R&D. Je vous suis très reconnaissante de m'avoir intégrée dans cette équipe où je me sens si bien. Cette ambiance de travail si agréable m'a permis d'aborder beaucoup plus facilement les hauts et les bas pendant ces trois années. Merci à Célinette qui a rejoint ORTESA récemment en ramenant beaucoup de gaieté et de chansons ; merci à toute l'équipe Purif (ou plutôt « Industrial design ») avec qui j'ai eu l'occasion de travailler pendant les 6 derniers mois, en particulier  mettre en oeuvre des procédés alternatifs pour améliorer le taux d'extraction, le rendement en actif, les interactions solutés/solvants des procédés industriels existants, tout en diminuant la durée totale du procédé, le nombre d'opérations unitaires, la consommation énergétique et l'impact global du procédé sur l'environnement ;  développer de nouveaux extraits notamment à partir de co-produits d'extraction au vu des quantités conséquentes générées ;  remplacer les solvants pétroliers et les solvants pouvant avoir un impact sur l'environnement, l'utilisateur ou le consommateur par des solvants alternatifs plus

« verts » ;

 accompagner scientifiquement l'implémentation industrielle des améliorations de procédés.

Afin de répondre à ces problématiques, ce manuscrit se décline en cinq chapitres se référant à l'intensification de procédés par des technologies innovantes, la substitution de solvants nocifs par des alternatives plus vertes et la valorisation de co-produits d'extraction en produits à haute valeur ajoutée.

Le chapitre I présentera une étude bibliographique sur l'éco-extraction des produits naturels en général. Le terme d'intensification de procédés et les principes de l'éco-extraction seront définis et mis en relation. Puis, pour chaque principe (relatifs à la matière première, au solvant, à l'énergie, au procédé, aux co-produits et à l'extrait final) seront présentés un constat de la situation actuelle, les bonnes pratiques à mettre en oeuvre pour s'inscrire dans la démarche d'éco-extraction et enfin des exemples de « success stories » initiés par des académiques ou des industriels. Les exemples ne se limiteront pas à un type de plante en particulier, cependant des exemples relatifs au romarin et au gingembre seront donnés dans la mesure du possible puisqu'il s'agit des matrices d'intérêt dans cette thèse.

Le chapitre II décrira les différentes méthodologies expérimentales utilisées dans cette Enfin, le chapitre V proposera un procédé inspiré de la bio-raffinerie pour valoriser les co-produits du gingembre. Il s'agira d'une bio-raffinerie « sèche » sans solvant ni eau ajoutés utilisant des technologies vertes. En effet, le press cake de gingembre récupéré après extraction du jus sera d'abord traité par micro-ondes (MHG : Microwave hydrodiffusion and gravity) pour obtenir une huile essentielle, puis par ultrasons dans son eau de constitution pour récupérer un extrait riche en composés phénoliques et un résidu riche en fibres et antioxydants. Les paramètres de chaque procédé micro-ondes et ultrasons seront optimisés pour maximiser les rendements d'extraction. Enfin, un bilan environnemental sera dressé et comparé à celui d'une bio-raffinerie mettant en oeuvre des procédés conventionnels (Figure 3). En résumé, les objectifs de ce travail de thèse sont précisément :

 D'intensifier le procédé d'extraction de composés d'intérêt à partir du romarin par l'utilisation de technologies innovantes ;  D'évaluer l'effet du ratio en éthanol dans des mélanges hydro-alcooliques sur la composition et l'activité d'extraits de romarin dans le but de développer un procédé inspiré de la bio-raffinerie ;  De valoriser les co-produits de fruits et légumes en produits à haute valeur ajoutée par un procédé inspiré de la bio-raffinerie.

Pour terminer, les principales conclusions de ce travail seront dégagées et des perspectives d'études futures seront proposées.

Analyses et interprétation

Bilan environnemental

I.1 INTRODUCTION

The aversion towards synthetic additives generated a great interest and a growing demand on natural extracts in the last decades. For example, in 2014, the overall market of antioxidants was about 1700 million euros of whom natural antioxidants accounted for 550 million euros.

Natural extracts can be sourced in huge number of plants materials and includes, as illustrated in Figure I-1, primary and secondary metabolites as antioxidants, essential oils (EO), proteins, fats, dietary fibers, dyes or even saponines [START_REF] Azmir | Techniques for extraction of bioactive compounds from plant materials: A review[END_REF][START_REF] Kaufmann | Recent extraction techniques for natural products: microwave-assisted extraction and pressurised solvent extraction[END_REF][START_REF] Shirsath | Intensification of extraction of natural products using ultrasonic irradiations-A review of current status[END_REF][START_REF] Zhang | Microwave assisted extraction of secondary metabolites from plants: Current status and future directions[END_REF]. They are largely used as ingredients in the food processing industry for their texturing, preservative or coloring properties [5][START_REF] Maqsood | Phenolic Compounds and Plant Phenolic Extracts as Natural Antioxidants in Prevention of Lipid Oxidation in Seafood: A Detailed Review[END_REF][START_REF] Shahid | Recent advancements in natural dye applications: a review[END_REF], and as active compounds in cosmetics or pharmaceuticals [8,[START_REF] Smit | Medicinal and pharmaceutical uses of seaweed natural products: A review[END_REF].

Conventionally, such extracts are obtained using solid-liquid extraction. Besides the only step of extraction, pre-treatment of plant material (drying, grinding…) and post-treatment of liquid extract (filtration, concentration, purification…) are also necessary to ensure global process efficiency. Such processes, particularly when they are not optimized, are often time and energy consuming, induce the use of huge amount of water or petroleum solvents harmful for environment and users and generate large quantity of waste. Moreover, resulting extract is not always safe as it may contain residual solvents, contaminants from raw material, or denatured compounds due to drastic extraction conditions. In this context, plant extraction specialists firstly aimed at intensifying their processes.

Principle of intensification is presented in Figure I-2. The objective is to obtain higher extraction efficiency and higher quality extract while reducing extraction time, number of unit operations, global energy consumption, quantity of solvent in the process, environmental impact, economical costs and quantity of waste generated [START_REF] Keil | Modeling of process intensification[END_REF]. In the last decades, with the increasing interest to environmental, economic and safety considerations, innovative alternatives with durable and green values have been hugely implemented in food processing, cosmetic and pharmaceutical industries. It was particularly initiated by the publication of the twelve principles of green chemistry [START_REF] Anastas | Green chemistry: Theory and practice[END_REF] and the twelve principles of green engineering [START_REF] Anastas | Desing through the twelve principles of green engineering[END_REF] which define the good practices to be adopted in order to engage in this demarche. Following this, plant extraction researchers and industrials met on January 2010 to define the term of "green extraction" and establish, in the same spirit of Anastas et al., the six principles of green extraction [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF]. These principles intend to act on the main inputs and outputs regarding a global extraction process: the raw material, the solvent, the energy, the process itself, the waste and by-products (organic or not) and the final extract (Figure I-3). By definition, green extraction "is based on the discovery and design of extraction processes which will reduce energy consumption, allows use of alternative solvents and renewable natural products, and ensure a safe and high quality extract/product". In this definition, the main ideas of intensification principle are identified. The listing of green extraction principles was established to guide scientist and industrials in their demarche towards green innovation, not only regarding the process, but in all aspects of solid-liquid extraction [START_REF] Chemat | Green Extraction of Natural Products: Concept and Principles[END_REF].

Extraction yield

 Principle 1: Innovation by selection of varieties and use of renewable plant resources.

 Principle 2: Use of alternative solvents and principally water or agro-solvents.

 Principle 3: Reduce energy consumption by energy recovery and using innovative technologies.

RAW MATERIAL

(PRINCIPLE 1)

PROCESS

WASTE AND BYPRODUCTS

(PRINCIPLE 4)

EXTRACT (PRINCIPLE 6)

 Principle 4: Production of by-products instead of waste to include the bio-and agrorefining industry.

 Principle 5: Reduce unit operations and favor safe, robust and controlled processes.

 Principle 6: Aim for a non-denatured and biodegradable extract without contaminants.

Hence, in this chapter, good practices guidelines regarding each principle are developed.

Plus, examples of success stories are presented in order to show the potential and the feasibility of such practices at different scales. The examples given are not limited to one kind of plant material, however particular applications regarding rosemary and ginger are raised since they are the two matrices of interest in this thesis.

I.2 PRINCIPLE 1: INNOVATION BY SELECTION OF VARIETIES AND USE OF

RENEWABLE PLANT RESOURCES.

I.2.1 Context

The increasing demand of natural products and extracts to answer the needs of food, cosmetic and pharmaceutic industries is leading to the over-exploitation of natural plant resources. This production of natural extracts has to take into account a number of issues, such as respect for the environment and human health or production with high yields, which are key issues for industrials. History reports several examples of plant extinction because of overutilization. More particularly, the large-scale uncontrolled harvesting of natural resources may carry the risk of making the species rare or even extinct. The preservation of biodiversity is therefore mandatory in the respect of future generations. In this context, in green extraction, fully renewable resources have to be favored either with intensive cultivation or in vitro growth of plant cells or organisms. Moreover, there is a need to integrate the raw material in an industrial vision regarding environment, social and economic aspects, in order to preserve natural resources.

I.2.2 Good practices guidelines

To limit the impact on the environment of processes and to produce extracts that meet the values of green extraction, a number of good practices should be implemented [START_REF]France Eco-Extraction, Guide des bonnes pratiques de l'éco-extraction[END_REF]:

 Integrate the raw material to an ecosystem vision including a social/ societal, environmental and economic diagnosis.

 Rely on standards such as ISO 26000 or relating to production monitoring.

 Implement protocols to promote the performance of the resource by varietal selection. The aim of varietal selection is to increase yields, produce varieties containing certain target compounds or select varieties adapted to region and climate.

 Support treatment technologies that (i) enable efficient production of crops and crop protection products (ii) meet the demands of an agriculture more friendly to environment and men with varieties resistant to pests and pathogens.

 Avoid cultures generating pollution, threatening biodiversity and competing with local vegetation or local food crops.

 Better manage and develop the inputs during cultivation (water, pesticides).

 Value health benefits of the extracts and enhance the diversity of products that can be obtained (to expand the plant resources).

I.2.3 Success stories

The integration of principle 1 in raw material sourcing can be performed by using renewable resources, by selecting some varieties of plant (high content in targeted compounds or absence of undesirable molecules) and by using new technologies. This section aims at presenting some success stories regarding such demarches.

I.2.3.1 Use of renewable resources

Currently, most medicines are extracted from plants. The anti-cancer paclitaxel (Taxol®) extracted from the bark of the western yew (Taxus brevifolia) is the best known example [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF]. The molecule of paclitaxel is presented in

I.2.3.2 Varietal selection

Plant composition varies widely among varieties. This variation is caused by several factors such as environmental factors (climate, soil and fertilization), but the most important factor determining the composition and the content of active compounds is the genetic variation. Thus, breeders have the opportunity and challenge to produce new varieties with modified compositions and improved contents of active compounds.

I.2.3.2.1 Improvement of Artemisinin content in Artemisia annua L. [14]

A big effort is running in the natural selection of varieties with much higher concentrations of active ingredients as the example of the production of artemisinin (Figure

I-6).
Artemisinin is known as an anti-malarial substance isolated from wormwood, Artemisia annua L., originating from Asia. The active principle of this plant is a sesquiterpene lactone with a peroxide bridge, which is present in the aerial parts of the plants at a concentration ranging from 0.01 to 0.05 %. Extracting this active substance turns out to be hardly cost effective because of the low concentrations in the plant. Much experimental work has been done to produce varieties of Artemisia annua L. with higher concentrations of artemisinin.

Currently some varieties present contents greater than 1 %.

I.2.3.2.2 Cassava with low cyanogenic glycosides content [17]

Cassava is one of the most important root crop in the world (241 million tons, FAO 2010). It is also the second most important staple crop in Africa and is used extensively for starch production in South East Asia. Most of cassava production is used for human consumption. However, the natural presence of cyanogenic glycosides, especially linamarin, is of concern in terms of food safety as it may release free cyanide (HCN). HCN is very toxic and lethal in high amounts. To reduce health problems associated with the ingestion of cassava products, the development of varieties with low cyanide content has been undertaken.

Traditional plant breeding has generated cultivars with high and also others with low levels of cyanogenic glycosides. The use of genetic modification has led to the development of varieties free from these compounds.

I.2.3.2.3 Claryssime project: sage rich in sclareol

So far, the market of sage has been driven by that of EO considering the rest of the plant as a by-product. However, this situation is changing and market requirements are evolving. Needs in EO (for fine perfumery mostly) are remaining stable contrary to the strongly developing demand for sclareol, another compound of interest that can be found in Sclareol is source of a hemi-synthesis molecule commonly called Ambrox, highly used for its olfactory power and high biodegradability. For regulatory reasons, functional perfumery is increasingly using Ambrox®, thus increasing the need for sclareol. Indeed, this molecule is used instead of gray amber of cachalots, formerly very prized and which completely disappeared. One of the aim of the project was to improve the agricultural production of sclareol by identifying the plant's genes involved in the synthesis and secretion of sclareol. These genes involved in the metabolism of sclareol were identified as well as the location of sclareol in the plant. More precisely, it was discovered that sclareol was stored in the cuticle of the calyx of flowers. Botanical varieties of grown clary sage were adapted to produce more sclareol and harvest period was correlated with optimal stage of maturity of plant for sclareol [START_REF]Claryssime -Projet sclaréol Presentation[END_REF].

I.2.3.3 Development of new technologies: Example of Plant milking [14]

A new technology known as "plant milking" was developed for the production and extraction of substances of interest, preventing the destruction of plant material. These plants are grown in a greenhouse in liquid medium. Actually, secretion and exuding of targeted substances through the roots in the culture medium are triggered by physical, chemical or biological stimulation (Figure I-8). These substances are then collected by standard extraction and purification methods. This process is particularly performed to produce active principles from rare plants, whose chemical synthesis is difficult and costly. Therefore, "plant milking" appears as an extraction way that respects biodiversity. For example, such process enabled the production of, among others, tropane alkaloids of pharmaceutical interest from Datura innoxia. In this case, harvesting yields of three times more secondary metabolites were obtained in one year compared to an equal area of field-grown plants. Good results were also obtained with garden rue (Ruta graveolens) which contains furocoumarins (substances used to treat eczema and psoriasis), and with edelweiss, rich in antioxidants. Regarding yew, "plant milking" yields much larger quantities of paclitaxel than traditional harvesting methods. Finally, considering a possible implementation of such technique at larger scale, it was calculated that a few hundred greenhouses would be sufficient to satisfy world demand in paclitaxel for one year.

I.3 PRINCIPLE 2: USE OF ALTERNATIVE SOLVENTS AND PRINCIPALLY

WATER OR AGRO-SOLVENTS.

I.3.1 Context

In solid-liquid extraction, it can be admitted that extraction efficiency strongly depends on the solvent. Indeed, even if process is optimized, if the solvent does not solubilize the solute after its release from raw material, it will be difficult to reach acceptable yields.

Moreover, beyond its high dissolving power, solvent has to be a good "extractant", meaning that it must penetrate sufficiently into raw material to "recover" molecules of interest from their location in the plant [START_REF] Moity | Chapter 1: In silico search for alternative green solvents[END_REF]. Dissolving phase actually occurs only in a second stage.

Therefore, a good compromise between extractant and dissolving properties must be achieved, which makes solvent selection even more complicated.

Conventional solvents generally used in plant extraction are presented in Table I-1.

They have the important advantage to present relatively low boiling point and low enthalpy of vaporization, which facilitates their removal after extraction and limits the energy consumption related to this step. Moreover, some of them are very selective towards targeted molecules, such as hexane for the extraction of lipophilic molecules. However, besides their obvious advantages, these solvents also present negative aspects. In most cases, they are petroleum-sourced (therefore obtained from non-renewable resources), VOC (Volatile Organic Compounds) emitter and harmful to human health and environment. Indeed, as

shown by the pictograms in Table I-1, they may be carcinogenic or even CMR (Carcinogenic, Mutagenic, and Reprotoxic) like hexane.

In this context, a growing aversion towards such solvents emerged. The increase of drastic legislation regarding their use in food, cosmetic or pharmaceutical fields (for example Directive n° 2010/59/UE or European Pharmacopeia) forced industrials and academics to find potential replacement solvents. Ideally, these alternative solvents may be comparable/improved in terms of efficiency, more environmentally friendly, safer for users and rather cheap. Finally, last but not least, they may present an acceptable boiling point in order to be easily removed and recycled after extraction without degrading final extract.

I.3.2 Good practices guidelines

The choice of the solvent is crucial in the demarche of green extraction. It must particularly ensure the durability of global process. To this end, good practices guidelines must be respected as far as possible [START_REF]France Eco-Extraction, Guide des bonnes pratiques de l'éco-extraction[END_REF]:

 Evaluation of a potential "solvent-free" alternative  Use of 100 % natural, natural origin, renewable or agro-sourced solvent (on the condition of having good knowledge, evaluation and control of potential related risks)

 Avoid the use of solvent which might affect the safety and health of production operators and consumers: it must not be a CMR or toxic (or present low toxicity); it must not induce allergenic effect and not belong to endocrine disruptors.

 Use of solvent suitable with industrial facilities  Prefer a solvent with high rate of recyclability (high bio-degradability and no bioaccumulation) to limit global process impact on environment  Use of solvent with low VOC emissions related  Use of solvent which limit energy consumption and cost of global process (solvent with low boiling point, low specific heat capacity and low enthalpy of vaporization).

 Ensure a maximal solvent recovery at the end of the process using various available techniques.

I.3.3 Success stories

One of the main challenges of current extraction field is the elimination or replacement with greener alternatives of harmful solvents (for users and environment). This part relates some success stories regarding this challenge. First of all, a solvent-free extraction process will be presented, followed by examples of new generation solvents with green values ("green solvents") and finally decision-making tools to assist this demarche of solvent substitution.

I.3.3.1 Solvent-free microwave extraction (SFME)

As indicated by principle 2's specifications, the ideal solvent in a green extraction process is actually the absence of solvent. In some cases, it is possible to develop solvent-free processes, particularly with water-rich materials. Among the available solvent-free extraction processes [START_REF] Vian | Chapter 2: Solvent free extraction : myth or reality ?[END_REF], SFME have been particularly investigated in last decade [START_REF] Chemat | Solvent-free extraction of food and natural products[END_REF][START_REF] Li | Solvent-free microwave extraction of bioactive compounds provides a tool for green analytical chemistry[END_REF].

First of all, SFME can be used as an alternative process to conventional Most examples of EO SFME are related in current literature: from oregano [START_REF] Bayramoglu | Solvent-free microwave extraction of essential oil from oregano[END_REF], from flowers [START_REF] Jiang | Solvent-free microwave extraction coupled with headspace single-drop microextraction of essential oils from flower of Eugenia caryophyllata Thunb[END_REF], from cardamom [START_REF] Lucchesi | Solvent free microwave extraction of Elletaria cardamomum L.: A multivariate study of a new technique for the extraction of essential oil[END_REF], from rosemary [START_REF] Tigrine-Kordjani | Kinetic Investigation of Rosemary Essential Oil by Two Methods: Solvent-Free Microwave Extraction and Hydrodistillation[END_REF], from salvia [START_REF] Villa | Salvia somalensis essential oil as a potential cosmetic ingredient: solvent-free microwave extraction, hydrodistillation, GC-MS analysis, odour evaluation and in vitro cytotoxicity assays[END_REF] and more generally from aromatic herbs [START_REF] Filly | Solvent-free microwave extraction of essential oil from aromatic herbs: From laboratory to pilot and industrial scale[END_REF][START_REF] Lucchesi | Solvent-free microwave extraction of essential oil from aromatic herbs: comparison with conventional hydro-distillation[END_REF][START_REF] Riela | Effects of solvent-free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the conventional production method[END_REF] and spices [START_REF] Lucchesi | An original solvent free microwave extraction of essential oils from spices[END_REF]. MHG has been hugely used to extract various compounds from various plant materials, particularly EO from rosemary and citrus [START_REF] Bousbia | Comparison of two isolation methods for essential oil from rosemary leaves: Hydrodistillation and microwave hydrodiffusion and gravity[END_REF][START_REF] Bousbia | A new process for extraction of essential oil from Citrus peels: Microwave hydrodiffusion and gravity[END_REF],

dyes from grape [START_REF] Al Bittar | An innovative grape juice enriched in polyphenols by microwave-assisted extraction[END_REF], fruit juices rich in phenolics and sugars from apricot and plums [START_REF] Cendres | An innovative process for extraction of fruit juice using microwave heating[END_REF][START_REF] Cendres | Comparison between microwave hydrodiffusion and pressing for plum juice extraction[END_REF],

antioxidants [START_REF] Périno-Issartier | Solvent Free Microwave-Assisted Extraction of Antioxidants from Sea Buckthorn (Hippophae rhamnoides) Food By-Products[END_REF] and phenolics from algae [START_REF] Pérez | Microwave hydrodiffusion and gravity processing of Sargassum muticum[END_REF]. In all cases, SFME enables to reduce drastically extraction time, from several hours with conventional HD to few minutes. Moreover, resulting extracts present improved organoleptic properties and are completely safe since no solvent is used in the procedure. The only requirement with such process concerns initial plant material moisture: to avoid any problem of burning during the process, initial raw material must be rich in water or previously humidified.

I.3.3.2 Use of greener solvents

The definition of solvent greenness is quite difficult. Currently, there is no systematic method to determine how "green" a solvent is. Several factors must be assessed, such as

GREEN SOLVENTS

Liquid polymers

modulate its polarity, which considerably increases the scope for the extraction of less polar molecules.

The first mean to decrease water polarity is to increase temperature and pressure. It Subcritical water have been used in various cases to extract lipophilic compounds, such as antioxidants and phenolics from rosemary, ginger or potato peel [START_REF] Carr | A review of subcritical water as a solvent and its utilisation for the processing of hydrophobic organic compounds[END_REF][START_REF] Basile | Extraction of Rosemary by Superheated Water[END_REF][START_REF] Ibañez | Subcritical Water Extraction of Antioxidant Compounds from Rosemary Plants[END_REF][START_REF] Jaapar | Prediction of solubilities for ginger bioactive compounds in hot water by the COSMO-RS method[END_REF][START_REF] Md Sarip | The kinetics of extraction of the medicinal ginger bioactive compounds using hot compressed water[END_REF][START_REF] Singh | Subcritical water extraction of phenolic compounds from potato peel[END_REF][START_REF] Plaza | Pressurized hot water extraction of bioactives[END_REF]. Globally, SWE appears as a fast, reliable, clean, green and environmentally friendly technique to extract polar, mid-polar and non-polar compounds from plant material. However, its use is limited in the case of thermosensitive compounds because of too high processing temperature.

Another way to decrease water polarity is the addition of surfactant or hydrotropes in the solvent [START_REF] Yazdi | Surfactant-based extraction methods[END_REF][START_REF] Dhapte | Advances in hydrotropic solutions: An updated review[END_REF]. Such products, by their very structure (Figure I-13), are able to solubilize low polarity compounds in water. Regarding hydrotropes, the hydrophobic tail is shorter. In solution, they don't form micelles (they don't have a CMC), but they self-aggregate gradually. However, they have a concentration threshold at which the solubility of hydrophobic compounds increases significantly: this threshold is called the minimum hydrotropic concentration (MHC) [START_REF] Petigny | Chapter 7: Water as green solvent for extraction of natural products[END_REF]. Various commercial surfactants/hydrotropes are available, they are classified in three categories: anionic, cationic, zwitterionic or non-ionic. Depending on raw material and

I.3.3.2.2 Bio-based solvents

By definition, bio-solvents are obtained completely or partially from renewable raw materials. As presented in Table I-4, they are derived from cereal crops (corn, wheat…), wood or generally from lignocellulosic material using fermentation processes or by synthesis in accordance with the principles of green chemistry. They can be as well integrated in biorefinery processes since cereal and wood by-products still remain high quality lignocellulosic materials. Bio-solvents are biodegradable, non-toxic and generate very low amount of VOC compared to petroleum solvents. Hence, in extraction field, they are good candidates to replace harmful solvents such as hexane. The replacement of hexane with bio-based solvents have been hugely investigated in current literature. Some of the most studied alternative are presented in Table I-4. Among them, Me-THF is the most promising since it enables to reach similar or improved yields regarding the extraction of fats from rapeseed, carotenoids from carrots and aromas from buds black current, in comparison with hexane [START_REF] Sicaire | Chapter 12. MeTHF as alternative solvent to hexane for extraction of natural products[END_REF]. Moreover, it is of great interest as it presents a low boiling point compared to other bio-based solvents, hence limiting the energy consumption related to its removal from final extract. HSP enable to characterize efficiently solute-solvent interactions according to the well-known "like dissolve like" principle. They are derived from the solubility parameter δH using Eq. I-1. They actually correspond to the three main molecular interactions which may take place between molecules, namely dispersion forces (δd), attraction forces/polarity (δp)

and hydrogen bonding (δh) [START_REF] Hansen | Chapter 1: Solubility parameters -An introduction[END_REF]. These three parameters define a 3D space where all solvents and solutes can be placed. To screen which solvent might potentially solubilize a given solute, the approach presented in Figure I-16 must be adopted. Firstly, the SMILES of solutes and solvents have to be generated and implemented in the software to calculate the HSP. Then, the solubility sphere of solute is determined. Any solvent located in this sphere is likely to solubilize the solute. Indeed, the closer the solute and solvent parameters are, the better the solubility is [START_REF] Benazzouz | Hansen approach versus COSMO-RS for predicting the solubility of an organic UV filter in cosmetic solvents[END_REF]. Solute-solvent distance D is defined according to Eq. I-2.

Eq. I-1

δH = (δd 2 + δp 2 + δh 2 ) 1/2
Eq. I-2 D = (4x(δd(solvent)δd(solute)) 2 +(δp(solvent)δp(solute)) 2 +(δh(solvent)δh(solute)) 2 ) 1/2 Potential miscibility between a solute and a solvent can also be quickly determined calculating the "Relative Energy Difference" (RED). It corresponds to the ratio between the distance D and the radius R of the solubility sphere (Eq. I-3). 0 < RED <1 indicates that a molecule is in the solubility sphere and is likely to solubilize the solute. However, RED > 1 corresponds to a poor solubility.

Eq. I-3. Therefore, the use of HSP could be a helpful tool to perform a first selection of potential solubilizing solvents regarding a solute. However this qualitative approach does not consider Van-der-Waals bonds and acid-base effects, that's why solvent selection can be completed with complementary software as COSMO-RS. The Conductor-like Screening Model for Real Solvents (COSMO-RS) is a method for molecular description and solvent screening based on a combination of quantum chemistry (COSMO) and statistical thermodynamics (RS) to determine and predict thermodynamic properties without experimental data [START_REF] Klamt | Prediction of the mutual solubilities of hydrocarbons and water with COSMO-RS[END_REF].

RED =

COSMO-RS is a two-step procedure: microscopic and macroscopic steps.

First, the COSMO model is applied to simulate a virtual conductor environment for the molecule of interest which is then embedded into a virtual conductor (Figure I-17 (a)). In such an environment, a surface is built on the molecule and it generates an important number of electrostatic charges. The structure and the charge distribution are then optimized to find the minimal energy of the system (molecule in its most stable state) thanks to algorithm-based calculations (Density Functional Theory). This charge density is called σ-surface (Figure

I-17 (b))

. This optimal distribution is afterwards segmented and reduced to a histogram called σ-profile (Figure I-17 (c)). The color code gives information about the charge density in each point of the molecule. The green color corresponds to a zero charge density (generally ascribed to carbon skeleton, σ = 0 on the histogram), the blue color to a positive charge density δ + (generally ascribed to hydrogen atoms, σ < 0 on the histogram) and the red color to a negative charge density δ -(generally ascribed to oxygenated and nitrogenized groups , σ > 0 on the histogram). Actually, the σ-profile traduces in 2D the information provided in 3D by the σ-surface. At this stage, the molecule of interest is isolated and does not take into account the molecules in its neighborhood. In order to consider a molecule as a solvent (or as a solute in a solvent) and quantify the interaction energy associated, an additional step based on statistical thermodynamic calculations is required. Solvent interactions are reduced to local interactions by pair of surface portions represented by charge density σ and σ'. All interactions of surfaces are assumed to be in close contact. These contacts can be ideals, noncomplementary or can highlight hydrogen bonding which generate energies of interactions.

The sum of these energies for a defined area is the interaction energy functional Eint (Eq. I-4).

Eq. I-4.

Eint = Emisfit + Ehb + Evdw

If a contact on a surface area aeff (effective contact area) is considered in the particular situation of complementary molecule (where σ = σ '), the interaction energy, also called misfit energy Emisfit, is equal to zero and the contact is "ideal." In the general case, there is a mismatch between the partners, σ ≠ σ ', therefore Emisfit is not zero. In the case where two opposite polarity surfaces are in contact, additional energy appears, hydrogen bonding (HB) energy Ehb. HB donors have a strongly negative screening charge density whereas HB acceptors have strongly positive screening charge densities. HB interaction can generally be expected if two sufficiently polar pieces of surface of opposite polarity are in contact. This energy is added to the electrostatic Coulomb energy from a σhb threshold. In addition to electrostatic misfit and HB interaction, Van der Waals interactions between surface segments are taken into account. The contribution of Van der Waals interactions is not dependent of its vicinity, this is not an energy of interaction but rather a contribution to the energy of the reference state.

After having established the concept of interaction energies on a given molecule surface, it is required to obtain a coherent model of molecules in solution. The σ-profile, Ps(σ), is actually the sum of σ-profiles of Pxi components, weighted by their molar fraction Xi (Eq. I-5).

Eq. I-5.

Ps(σ) = Ʃ Xi . Pxi (σ)
The chemical potential of a surface segment with screening charge densities in an ensemble described by normalized distribution function ps(σ) is noted μs(σ). This approach can first allow estimating the affinity of a molecule depending on the contacting charge density σ. The molecule is considered as a solvent and this affinity is represented as a σpotential curve μs(σ). Secondly, the estimation of the affinity of a molecule i in a solvent S is translated by computing its chemical potential μi S (Kcal.mol -1 .A 2 ). This chemical potential is obtained by integration of the σ-potential over the surface of i (Figure I-17 (d)). The σpotential is calculated from the statistical thermodynamics of molecular interaction based on the obtained σ-profile. This chemical potential μiS, given in the equation below, is the standard chemical potential minus RTln(xi) which allows the prediction of almost all thermodynamic properties of compounds or mixtures including solubility.

Eq. I-6.

μi S = μi C,S +∫ Pxi (σ).μS(σ).dσ With μi C,S the combinatorial contribution to the chemical potential resulting from the derivation of the combinatorial free energy expression. In practice, the relative solubility of various solutes in various solvents is calculated from the following equation [66]:

Eq. I-7. log10 (xi) = log10 [ ( - -∆ , )
] Generally, energy consumption related to extraction processes can be reduced adopting four main approaches: optimizing existing process; recovering the energy released during the process; assisting existing processes, particularly with innovative technologies; and using innovative processes [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF].

With

I.4.2 Good practices guidelines

In the demarche of green extraction, the decrease of energy consumption can be achieved using different strategies [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF][START_REF]France Eco-Extraction, Guide des bonnes pratiques de l'éco-extraction[END_REF]: "the act of obtaining the best result possible or the effort for achieving the optimal solution under a given set of circumstances. In design, development, processing operation, and maintenance of engineering systems, common goals are either to minimize the cost or maximize the desired profits as product quality and operation yield" [START_REF]Extraction optimization in food engineering[END_REF]. Thus, in this demarche, energy consumption must be decrease as far as possible since it is related to high costs. In most scientific studies, optimization of process is performed regarding only one kind of parameter which is the quality of final extract (yield and activity) [START_REF] Liadakis | Multiresponse optimization of an extraction procedure of carnosol and rosmarinic and carnosic acids from rosemary[END_REF][START_REF] Ok | Optimization of Extraction Conditions for the 6-Shogaol-rich Extract from Ginger (Zingiber officinale Roscoe)[END_REF][START_REF] Chen | Optimization of extraction of phenolics from leaves of Ficus virens[END_REF][START_REF] Fu | Extraction optimization of oleanolic and ursolic acids from pomegranate (Punica granatum L.) flowers, Food Bioprod[END_REF]. Operating parameters (temperature, duration, pressure, pH…) are thus selected to maximize this criterion, despite they might be related to high energy consumption. Therefore, with the increasing interest in energy saving, more and more processes or equipment are designed considering this aspect.



PROBLEM FORMULATION

• Definition of variables/controlled parameters

STORAGE DIRECT USE

INDIRECT USE

Some societies have already developed equipment to ensure the recycling of fatal heat, such as Belfort area engineers which developed a motor able to generate mechanic or electric from an external heat source (over than 150 °C) [START_REF] L'observatoire | La récupération de la chaleur fatale inspire l'innovation[END_REF].

In extraction field, most processes are performed at solvent boiling point and therefore need an external heat source to reach wanted temperature (generally with boiler at industrial scale). Depending on the solvent, energy input might be more or less important. Basil et al.

published a work at laboratory scale about extraction of flavor compounds from rosemary by superheated water [START_REF] Basile | Extraction of Rosemary by Superheated Water[END_REF]. This process was compared with conventional steam distillation in terms of extraction efficiency and energy and water costs. Water is one of the solvents which need the highest energy to be heated and converted at gaseous state. Working under pressure enables to decrease the energetic input. Indeed, whereas 2550 kJ/kg are needed to convert water at 30 °C to steam at 100 °C, only 505 kJ/kg are necessary to heat water from 30 °C to 150 °C under 15 bars. Plus, the study also claimed that much more heat could be recycled in a superheated water extraction, depending, however, on heat exchangers size. Heat advantage of superheated water extraction per kg of water is announced to be about 20 compared to steam distillation, which makes it viable for up-scaling purpose. Therefore, when designing a new process or optimizing an existing one, energy advantage related and potential to recover heat must be taken into consideration as far as possible.

I.4.3.3 Assistance to existing processes

When conventional extraction processes are not enough efficient to recover acceptable yields of specific compounds of interest from raw material, it is possible to intensify and assist the process with innovative technologies. Ultrasound (US) or MW can be used for this purpose. They have been hugely employed to intensify extraction of various compounds from various plant materials [START_REF] Alupului | Ultrasonic vs. microwave extraction intensification of active principles from medicinal plants[END_REF][START_REF] Bagherian | Comparisons between conventional, microwave-and ultrasound-assisted methods for extraction of pectin from grapefruit[END_REF][START_REF] Charpe | Extraction of glycyrrhizic acid from licorice root using ultrasound: Process intensification studies[END_REF][START_REF] Barrera Vázquez | Comparisons between conventional, ultrasound-assisted and microwave-assisted methods for extraction of anthraquinones from Heterophyllaea pustulata Hook f. (Rubiaceae)[END_REF][START_REF] Cardoso-Ugarte | Microwave-assisted extraction of betalains from red beet (Beta vulgaris)[END_REF][START_REF] González-Nuñez | Focused microwaves-assisted extraction of theobromine and caffeine from cacao[END_REF][START_REF] Milutinović | Microwave-assisted extraction for the recovery of antioxidants from waste Equisetum arvense[END_REF][START_REF] Dahmoune | Pistacia lentiscus leaves as a source of phenolic compounds: Microwave-assisted extraction optimized and compared with ultrasound-assisted and conventional solvent extraction[END_REF][START_REF] Lianfu | Optimization and comparison of ultrasound/microwave assisted extraction (UMAE) and ultrasonic assisted extraction (UAE) of lycopene from tomatoes[END_REF]. Generally, it results in the decrease of extraction duration and energy consumption compared to conventional process, for similar or enhanced extraction yields. In the case of rosemary, the application of US or MW to extraction media enabled to increase by three times the yield of total phenols extracted compared to corresponding conventional extraction [START_REF] Bellumori | Selective recovery of rosmarinic and carnosic acids from rosemary leaves under ultrasound-and microwave-assisted extraction procedures[END_REF]. US technology was also employed by Paniwnyk et al. to intensify antioxidants extraction from rosemary, and it resulted once again in improved extraction yields [START_REF] Paniwnyk | The enhancement and scale up of the extraction of anti-oxidants from Rosmarinus officinalis using ultrasound[END_REF]. As another example, MW were used to assist ginger solvent extraction, and as with US, greater yields were obtained in a drastically reduced extraction time (compared to Soxhlet) [START_REF] Alfaro | Influence of solvent, matrix dielectric properties, and applied power on the liquid-phase microwave-assisted processes (MAP TM ) extraction of ginger (Zingiber officinale)[END_REF]. Fundamentals of US and MW are described in the following parts.

I.4.3.3.1 Principle of US

US are mechanical waves that can propagate in an elastic medium and that have a higher wave frequency (20 kHz to 10 MHz) than sounds audible to humans (10 Hz to 20 kHz). Ultrasonic wave is characterized by the frequency f (in Hz), the wavelength λ (in m), the celerity c (in m/s), and the power P (in W) that quantify the ultrasonic energy provided by US to the system. This power per unit of US emitting surface defines the ultrasonic intensity (UI) (W/cm 2 ). Power can as well be related to the volume submitted to US, corresponding in this case to the power density (PD) (W/cm 3 ) [START_REF] Pétrier | Ultrasons et sonochimie[END_REF]. Generally, ultrasonic effect is characterized by various physical and chemical phenomena, including agitation, vibration, pressure, shock waves, shear forces, microjets, compression and rarefaction, acoustic streaming, cavitation and radical formation [START_REF] Tiwari | Ultrasound: A clean, green extraction technology[END_REF]. Where PA: maximal amplitude of the pressure of the wavelength f: frequency t: time I: ultrasonic intensity ρ: density of the medium c: velocity of the wave in the medium Compression phase corresponds to a positive pressure whereas rarefaction phase corresponds to a negative pressure. Such alternating pressures causes distention and connection between molecular groups in the medium . According to the medium, negative pressure is more or less extended. During rarefaction, beyond a certain distance between molecules, local pressure falls below the vapor pressure of the liquid, generating voids in the medium. These voids correspond to cavitation bubbles formed from dissolved gases. Depending on their or ultrasonic conditions, these bubbles will be stable or will implode in the medium. This phenomenon of creation, expansion and implosive collapse is called the acoustic cavitation [START_REF] Sicaire | Solvants alternatifs et techniques innovantes pour l'éco-extraction des huiles végétales à partir de graines oléagineuses[END_REF][START_REF] Pétrier | Ultrasons et sonochimie[END_REF][START_REF] Adam | Chapitre 4: Extraction assistée par ultrasons[END_REF][START_REF] Tiwari | Ultrasound: A clean, green extraction technology[END_REF]. Cavitation bubbles are divided in two categories, corresponding namely to transient cavitation and stable cavitation. Stable bubbles exist for several cycles of compression and rarefaction, therefore their lifetime is relatively long. In contrast, transient bubbles exist for a very short period of time, and collapse violently. This collapse corresponds actually to an implosion which generates temperatures and pressures superior to 2000 °C and 500 bar respectively locally in the medium. During UAE, when this phenomenon occurs on plant material surface, microjets and shock waves are generated directly towards the surface

As illustrated in

Frequency (Hz)

(Figure I-23).
It results in cell disruption, and consequently in a better solvent penetration in vegetable cell and a better mass transfer of solutes to the solvent [START_REF] Tiwari | Ultrasound: A clean, green extraction technology[END_REF][START_REF] Toma | Investigation of the effects of ultrasound on vegetal tissues during solvent extraction[END_REF].

As mentioned in previous lines, ultrasonic frequency determines US applications (power US for extraction/processing and diagnostic US for non-destructive analytical technique). Regarding power US, besides UI the main parameters influencing ultrasonic cavitation and more generally UAE are the plant material, the solvent, the temperature and the presence of dissolved gases. Most of these factors can have influence over each other, particularly solvent properties which are strongly temperature-dependent. The interaction between an electromagnetic field and a material (plant, solvent) depends on its dielectric properties. Such properties are characterized by the dielectric constant (or permittivity) Ɛ' and the dipole moment (or dielectric loss factor) Ɛ''. By definition, the dielectric constant of a molecule corresponds to its capacity to be polarized by an electric field and the dipole moment to its ability to convert MW energy into heat [START_REF] Chemat | Chapitre 5: Extraction assistée par micro-ondes[END_REF][START_REF] Thostenson | Microwave processing: fundamentals and applications[END_REF]. From Ɛ' and Ɛ'' can be calculated the dissipation factor (tan δ) using Eq. I-10.

Eq. I-10.

tan δ = Ɛ''/ Ɛ' MW will interact preferentially with molecules presenting a high dielectric constant.

Generally, they are polar or have a dipolar moment. Under MW, these molecules attempt to align with the electric field which switches approximately 2.5 billion times per second. Since there are internal interactions between molecules (hydrogen bonds or Van der Waals forces), this alignment is done with resistance, causing molecular friction. The sum of dipolar rotation, molecular friction and molecular collisions results in heat generation in the medium. Hence, heating occurs from the inside to the outside of material, unlike conventional heating when heating is done by conduction and convection, from the outside to the inside

(Figure I-26).
Moreover, there is a heating selectivity towards polar molecules. In plant extraction, depending on the aim of the experiment, it is possible to focus MW heating on solvent (in this case a polar solvent must be selected), directly on plant material (in this case an apolar solvent rather transparent to MW must be chosen) and even to perform extraction without solvent (MW will focus on constituent water of plant material). containing the sample which will be submitted to MW. Finally, in laboratory and industrial equipment, a monitoring system is generally added to the system in order to control MW power, time, temperature and pressure. MW can be applied either in monomode or multimode. In monomode, the application of MW is performed thanks to a cavity that maintains a single mode of propagation of the

Subcritical water ECOEXTRACTION INNOVATIVE PROCESSES

In much cases, these innovative technologies appear as energy efficient since they enable to reach maximal yields in reduced extraction time. Performed upstream from the main process, they permit an optimal pre-treatment of raw material. For example, US pre-treatment was performed for 30 min prior to HD of Carum carvi L. seeds. It resulted in rapid release of EO during HD, that is 80 % of EO recovery in 30 min against 90 min without pre-treatment Depending on the type of raw material processed and the technologies employed, the quantity of waste produced can vary considerably. As presented in Table I-7, in some cases, more than 50 % of processed raw material is considered as waste and by-products at the end of process.

Juice (from fruits and vegetables) and vegetable oil (from oleaginous) productions are particularly concerned since 30-50 % and 40-70 % of processed raw material respectively are regarded as waste and by-products at the end of process.

Table I-7. Percentage of food waste and by-products generated by different processes (from [START_REF] De Las Fuentes | Awarenet: Agro-food wastes minimization and reduction network[END_REF]).

Production processes Percentage of waste and by-products (%)

Corn starch production 41 -43

Fruits and vegetables juice production 30 -50

Fruits and vegetables processing and preservation 5 -30

Potato starch production 80

Sugar production from sugar beet 86

Vegetable oil production 40 -70

Wheat starch production 50

White and red wine productions 20 -30

The type of waste is very diverse since it is directly raw material-and processdependent. Table I-8 illustrates the large variety of residues which can be obtained from only one kind of raw material. Therefore, in a context of population growth, decline in agricultural productivity, increase in the productivity costs and underutilization of available resources, a way to manage at best this waste is urgently required [START_REF] Muragan | Chapter 2: Current state-of-the-art of food processing by-products[END_REF].

Table I-8. Type of residues from different foodstuffs after processing (from [START_REF] De Las Fuentes | Awarenet: Agro-food wastes minimization and reduction network[END_REF]).

Beyond the current waste and by-products management options, the production of food ingredients is the most cost-profitable for industrials, followed by the animal feed, the energy recovery, the land spreading and finally the land filling which relates to a negative • Composting and land application

• Land filling In this context, food processing and extraction by-products appear as good candidates for valorization. This demarche fits perfectly with the emerging bio-refinery concept which aims at a complete exploitation of a biomass and its different building blocks. The different parts can be transformed afterwards into bio-energy (heat, fuel and electricity) and bio-based products (foodstuffs, chemicals and biomaterials), using extraction, fractionation and conversion processes with particular facilities or network of facilities [START_REF] Cherubini | The biorefinery concept: Using biomass instead of oil for producing energy and chemicals[END_REF]. of their richness in various nutrients. This is the case for edible oil cakes which present, after processing, a protein content ranging from 15 % to 50 %, making them ideal candidates to supplement animal diet and enhance production efficiency. As an example, the diet of laying hens was supplemented with 10-20 % of processed flaxseed and it resulted in the production of high quality eggs ("omega eggs") valuable for their balance of unsaturated fatty acids [START_REF] Chandrasekan | Chapter 13: Oil seeds[END_REF]. Flaxseed by-products were also added to beef cattle diet and engendered an improvement of animal performance and carcass value [START_REF] Drouillard | Flaxseed and flax seed products for cattle: Effects on health, growth performance, carcass quality and sensory attributes[END_REF][START_REF] Maddock | The effect of processing flax in beef feedlot rations on performance , carcass characteristics and trained sensory panel ratings[END_REF]. In another case, distillated rosemary leaves (by-product resulting from EO extraction) were transformed into pellets and incorporated in pregnant sheep diet in 0, 10 % and 20 % proportions. Effect on cooked lamb fillets was assessed and it resulted in decline of lipid oxidation and rancidity incipient due to the presence of antioxidant compounds. Thus, shelf life of lamb-based dishes can be extended by feeding ewes with such pellets [START_REF] Nieto | Effects in ewe diet of rosemary by-product on lipid oxidation and the eating quality of cooked lamb under retail display conditions[END_REF]. It was also showed that sheep diet supplementation with distillated rosemary leaves improved significantly fatty acids profile of lamb meat, with an increase in polyunsaturated and unsaturated fatty acids content and a decrease in saturated fatty acids rate [START_REF] Martínez | Incorporation of by-products of rosemary and thyme in the diet of ewes: effect on the fatty acid profile of lamb[END_REF].

Waste and byproducts management options

Beyond the various by-products, some of them have the ability to replace more traditional feed dedicated to livestock because of their specific composition. It is the case of ginger waste meal resulting from oleoresin extraction process: it can substitute maize in animal diet thanks to its high concentration in carbohydrates. A study carried out by Omage et al. also showed that rabbit diet supplemented with such ginger by-product induced hypocholesterolemic and hypolipidemic effects without affecting growth performance [START_REF] Omage | The effect of ginger (<i>Zingiber officinale<i> Roscoe) waste meal on growth performance, carcass characteristics, serum lipid and serum cholesterol profiles of rabbit[END_REF].

Finally, some by-products cannot be used in their native form to feed livestock since their composition is not compatible with their diet. As an example, coffee pulp (by-product of coffee processing) must be free of tannins, caffeine and other polyphenols to avoid any antinutritional issue in the final feedstock. However, the compounds which must be removed from the by-products might have potential interest in other markets. Plus, others by-products such as sugarcane tops (representing 5 % to 10 % of total cane production) offer very low content in essential nutrient (as proteins or minerals) and don't fulfill animal nutritional requirement. To increase their nutritive value, they may be transformed into silage using a specific process. As positive point, the generated product is particularly palatable and attractive to livestock [START_REF] Alemzadeh | Effect of different levels of sugarcane top silage on milk production of dairy cattle[END_REF].

I.5.3.2 Extraction of high value compounds

Food and extraction by-products offer a large variety of valuable compounds, as illustrated in Figure I-31 for fruits and vegetables residues. Beyond the potential products, we can cite antioxidants, proteins, EO, or dietary fibers. They can be recovered using various pretreatment and extraction techniques, from the most conventional to the most innovative [START_REF] Arshadi | Pre-treatment and extraction techniques for recovery of added value compounds from wastes throughout the agri-food chain[END_REF]. products, many of them deal with fruit and vegetables residues. Indeed, as examples, polyphenols were extracted from ginja cherry [START_REF] Piccirillo | High Added-Value Compounds with Antibacterial Properties from Ginja Cherries By-products[END_REF], grape [START_REF] Torres | Valorization of Grape (Vitis vinifera) Byproducts. Antioxidant and Biological Properties of Polyphenolic Fractions Differing in Procyanidin Composition and Flavonol Content[END_REF][START_REF] Kammerer | Recovery of polyphenols from the by-products of plant food processing and application as valuable food ingredients[END_REF], apple [START_REF] Kammerer | Recovery of polyphenols from the by-products of plant food processing and application as valuable food ingredients[END_REF][START_REF] Massini | Valorisation of apple peels[END_REF] or citrus by-products [START_REF] Matharu | Opportunity for high value-added chemicals from food supply chain wastes[END_REF][START_REF] Mamma | Biotransformation of Citrus By-Products into Value Added Products[END_REF] using different techniques. Rosemary by-products from EO industry were also valorized to recover specific powerful antioxidants: RA, CA, carnosol (CO), caffeic acid and chlorogenic acid. Rosemary waste was submitted to solid-liquid extraction with 96 % ethanol for 4 h. Authors suggested that the previous EO extraction would have modified the plant structure, favoring consequently antioxidants extraction in the next steps. However, some degradation phenomenon were testified by higher amounts of CO compared to CA in the final extract [START_REF] Navarrete | Valorization of solid wastes from essential oil industry[END_REF].

I.5.3.2.

Proteins

Oilseeds by-products generally contain between 15 and 50 % proteins and are consequently a common source of protein products. The treatment of oilseeds by-products in acidic or neutral medium leads to a protein concentrate (almost 70 % proteins) after elimination of non-protein compounds by precipitation. Oilseeds by-products can also be treated in alkaline and neutral medium to solubilize proteins and carbohydrates and generate a protein isolate (more than 95 % proteins) after further purification steps. Alternative methods can also be performed in order to enhance recovery rate and to avoid denaturation of proteins.

As an example, in the case of de-oiled rice bran, conventional alkali hydrolysis was replaced by hydrolysis in subcritical water at 200 °C for 30 min. It resulted in improved extraction yields and a final product exhibiting high antioxidant activity [START_REF] Sereewatthanawut | Extraction of protein and amino acids from deoiled rice bran by subcritical water hydrolysis[END_REF].

I.5.3.2.3 Dietary fibers

Dietary fibers can be valorized for their properties of texture and their health benefits in human diet. They are divided into soluble (pectin, gum) and insoluble (cellulose, most hemicellulose and lignin). Their isolation from by-products can be performed as a last process after the extraction of other valuable compounds (antioxidants, dyes or proteins). The most current by-products for dietary fibers production are citrus peels, and apple pomace [START_REF] Kammerer | Recovery of polyphenols from the by-products of plant food processing and application as valuable food ingredients[END_REF][START_REF] Mamma | Biotransformation of Citrus By-Products into Value Added Products[END_REF][START_REF] Schieber | A new process for the combined recovery of pectin and phenolic compounds from apple pomace[END_REF][START_REF] Figuerola | Fibre concentrates from apple pomace and citrus peel as potential fibre sources for food enrichment[END_REF]. Regarding pectin extraction, dried by-products are generally extracted at high temperature in acidic medium (pH 2.5) and pectin is afterwards precipitated by the addition of alcohol [START_REF] Kumar | Extraction and characterization of pectin from apple pomace and its evaluation as lipase (steapsin) inhibitor[END_REF]. The further purification steps consist in washing the previous precipitate with acidified and alkalinewater, and finally neutral alcohol. Insoluble fibers extraction, on the other hand, includes microbial fermentation, chemical and mechanical treatments.

I.5.3.2.4 Essential oils and aromas

Beyond the various food and extraction residues, the major sources of EO are the citrus by-products and more precisely the peels. Depending on the variety, essential content ranges between 0.05 and 5 %. Citrus EO (and more particularly those of lemon and orange) are mainly composed of limonene (until 95 %) [START_REF] Verzera | Biological lemon and sweet orange essential oil composition[END_REF] which can be valorize as agro-sourced solvent and be used for plant extraction to replace hexane [START_REF] Virot | Total Lipid Extraction of Food Using d-Limonene as an Alternative to n-Hexane[END_REF]. Various techniques are available to extract EO from citrus residues, from traditional processes as HD to the most intensified with supercritical fluids, MHG or DIC [START_REF] Filly | Solvent-free microwave extraction of essential oil from aromatic herbs: From laboratory to pilot and industrial scale[END_REF][START_REF] Mamma | Biotransformation of Citrus By-Products into Value Added Products[END_REF][START_REF] Rezzoug | Study of a new extraction process: controlled instantaneous decompression. Application to the extraction of essential oil from rosemary leaves[END_REF].

Another ways to generate aroma from by-products are the microbial synthesis or the bioconversion. Indeed, some by-products such as apple pomace or cassava bagasse can be used as substrate to produce fruity aroma [START_REF] Dastager | Chapter 6: Aromas compounds[END_REF].

I.5.3.3 Development of bio-refinery

Bio-refinery concept (Figure I-32) aims at total valorization of a biomass into its different building blocks to generate valuable bio-chemicals or energy, using chemical, physical and thermal processes. The development of bio-refinery is increasing since it is not selective with respect to the type of biomass, and a large range of very various products can be generated. Plus, the major part of available by-products contain various compounds of interest (EO, pectin, proteins…) which could be recovered in a single integrated process. With definitive economic and environmental advantage, it is a universal tool that should be more developed at industrial level.

Figure I-32. The plant bio-refinery concept (adapted from [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF]). Indeed, in both cases, from the inputs (biomass or fossil resources) are generated several products (outputs) using a multi-step process. However, the products obtained with the conventional refinery are mainly dedicated to energy and fuel sector, unlike bio-refinery where the balance between bio-chemicals and bio-energy generated is more equilibrated. An ideal bio-refinery aims at producing high-value low volumes to enhance the profitability and low-value high volumes which will be converted in energy using further operation units.

Currently, bio-refineries can be differenced in two categories according to the kind of raw material selected as input: the first and the second generation bio-refineries. As illustrated in Figure I-34, the first generation bio-refinery (or "whole-crop biorefinery") uses directly agricultural biomass (as wheat, rice, maize or colza) and generates mainly bio-fuels such as bio-ethanol or bio-diesel. Bio-ethanol is produced from biomasses rich in starch or sugars (such as wheat, sugar beet or corn) via an enzymatic hydrolysis followed by a fermentation step. Using this process, some compounds can also be generated in a secondary way, as the polylactic or the succinic acids. Regarding bio-diesel, it is generated from biomasses rich in vegetable oil and triglycerides via a transesterification step, which can be also associated to the production of secondary bio-chemicals as methyl esters of fatty acids or surfactants. This efficient and alternative production of biofuels appears as a good way to meet the challenge of fossil fuels replacement. However, first generation biorefineries are currently controversial since they encourage the competition between the production of agricultural raw material dedicated to the food sector and those dedicated to the In the case of second generation bio-refinery (or "lignocellulose feedstock biorefinery"), inputs correspond to non-food biomass. Bio-fuels and bio-chemicals are produced from lignocellulosic material including residues and waste from agriculture, forestry or food industry [START_REF] Cherubini | The biorefinery concept: Using biomass instead of oil for producing energy and chemicals[END_REF][START_REF] Laurent | Le bioraffinage, une alternative prometteuse à la pétrochimie[END_REF]. It corresponds to the hugest source of renewable carbon and the available biomasses are extremely diverse. Lignocellulosic biomass is composed of four fractions at various proportions: 40-60 % cellulose, 20-40 % hemicellulose, 10-25 % lignines and 10 % inorganic minerals and organic extractives (phenols, terpenes, alkaloids…) [START_REF] Wyman | Alternative fuels from biomass and their impact on carbon dioxide accumulation[END_REF][START_REF] Mohan | Pyrolysis of Wood/Biomass for Bio-oil: A Critical Review[END_REF]. From these structural compounds are produced the second generation bio-fuels (or "cellulosic biofuels") and bio-chemicals, using thermochemical or biochemical ways

(Figure I-34).
Thermochemical conversion includes essentially thermal processes such as combustion or pyrolysis. Regarding biochemical processes, the anaerobic digestion, the acid or enzymatic hydrolysis, followed by the fermentation of produced sugars are commonly performed.

Generally, a previous mechanical or chemical pre-treatment is necessary to break down the lignocellulosic material and make available the cellulose, hemicellulose and lignins [START_REF] Fitzpatrick | A biorefinery processing perspective: Treatment of lignocellulosic materials for the production of valueadded products[END_REF]. (bio-ethanol, bio-butanol, bio-hydrogen, bio-methane), organic acids (fatty acids, citric, lactic and succinic acids), bio-surfactant, bio-fertilizers and polysaccharides [START_REF] Zhang | Biorefinery approach for cassavabased industrial wastes: Current status and opportunities[END_REF]. In another case, palm-based waste was used to produce bio-compost, bio-plastics, bio-adsorbent, bio-diesel, bio-composite, bio-vanillin, bio-ethanol and bio-butanol [START_REF] Ali | Sustainable and integrated palm oil biorefinery concept with value-addition of biomass and zero emission system[END_REF].

Beyond the potential natural resources, the case of olive biomass was hugely investigated for bio-refinery. Olive oil processing generates huge amount of very varied waste (olive tree, leaves, olive pomace, olive stones or whether wastewater) which can be valorized.

In their review, Romero-García et al. showed the large range of compounds which can be recovered from olive biomass. Conventional bio-refinery (CBR) processes such as fermentation or enzymatic hydrolysis can be used to obtain as examples ethanol, lignin, oligosaccharides or antioxidants (oleuropein, tyrosol and hydroxytyrosol). These compounds can be afterwards precursors to other conversion processes leading to high value biochemicals [START_REF] Romero-García | Biorefinery based on olive biomass. State of the art and future trends[END_REF]. Such as olive biomass, orange peel waste is as well an ideal candidate for bio-refinery. Huge amounts are generated each year, due to the production of juice, and its composition offers a wide variety of valuable compounds. Indeed, after processing, the waste and by-products (about 50 % of initial fruit) are mainly composed of skin, pulp and seeds, which are source of EO, fatty acids, organic acids, sugars, enzymes, flavonoids or whether pectin. To valorize completely the orange peel waste, Boukroufa et al. developed a solventfree bio-refinery with green processes and obtained successively EO, polyphenols and pectin [START_REF] Boukroufa | Biorefinery of orange peels waste: A new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil, polyphenols and pectin[END_REF]. The experimental diagram of this study is presented in Generally, a whole extraction process is composed of following essential steps [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF]:

(1) Plant material pre-treatment: raw material must be previously dried and ground to increase surface contact area and solvent penetration level;

(2) Solid-liquid extraction with appropriated solvent;

(3) Solid-liquid separation by filtration or centrifugation;

(4) Solvent removal and recycling under vacuum to eliminate every trace of residual solvent in final extract.

Such process is often very long, and results in high energy consumption, particularly due to fourth step. To overcome this problem, intensification may be achieved, for example by designing smaller size units and by reducing the number of unit operations. Ideally, it may result in a better use of process inputs (raw material, energy…), a superior control of global process and a reduced global environmental footprint.

I.6.2 Good practices guidelines

Beyond energy efficiency described (Principle 3), a process must present other essential characteristics to meet the definition of green extraction process [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF][START_REF]France Eco-Extraction, Guide des bonnes pratiques de l'éco-extraction[END_REF]: This equipment proves a perfect match with principle 5 requirements. Indeed, it is extremely compact as six extractions can be performed at a time in a reduced space.


Moreover, it enables to obtain reliable results with excellent reproducibility. Solvent recovery is about 90 % and water consumption is limited, which permit to save energy and money.

Finally, last but not least, the process is operator-friendly since it is easy to use and safe (user exposure to solvent is minimized).

I.7.2 Good practices guidelines

To be considered as an "eco-extract", an extract must present most of the following For a better understanding of these different characteristics, each of them are further developed below.

I.7.2.1 Naturalness

The concept of naturalness is quite difficult to define, particularly in the case of plant extracts where the definition of a genuine natural extract is not clear. According to REACH legislation [148], a natural substance is "a naturally occurring substance as such, unprocessed

Quality

Legislation

Ecoextract

or processed only by manual, mechanical or gravitational means, by dissolution in water, by flotation, by extraction with water, by steam distillation or by heating solely to remove water, or which is extracted from air by any means. This definition includes that the substance must not be chemically modified, in other words its molecular structure must remain unchanged independently of the process performed (even chemical)." Thus, according to this legislation, olive oil or fruits and vegetables juices for example can be considered as "natural". However, this definition does not bring any details about solvent extraction process, excepted that it can be performed with water to ensure the naturalness of final extract. Thus, the naturalness of extracts obtained with such process is controversial and different points of view are represented. In some cases, solvent extraction is considered as a physical process, and the generated extract is considered as "natural", provided that solvent is eliminated at the end of the process. It is the case for favoring substances dedicated to foodstuffs governed by Decree n°91-366 (April 11 th 1991). In other cases, the naturalness of final extract is commanded by the type of solvent used for extraction which must be natural or natural origin to ensure naturalness. Still others refute the naturalness of extracts when they are obtained by solvent extraction other than water [START_REF]Direction Générale de la Concurrence, de la Consommation et de la Répression de Fraudes (DGCCRF)[END_REF]. Therefore, naturalness of extract obtained by solvent extraction is open to debate. Finally, last but not least, the global naturalness of an extract is also governed by the nature of initial plant material, which must be provided by a wellreasoned sourcing as far as possible.

It can be noticed that naturalness is very often associated to "organic" aspects. As an example, Ecocert and Cosmos certifications are essential in cosmetic sector and deal with both aspects. They are associated to detailed guides governing the chemicals and solvents authorized, as well as the processes and facilities adapted to produce certified organic and natural extracts or product [150,[START_REF] Ecocert Greenlife | Référentiel ECOCERT, Cosmétiques écologiques et biologiques[END_REF]. Various other appellations or labels referring to naturalness can be found on extracts or final products packaging in the different sector activities . Each of them are associated to a specific charter of good practices, relating to the type of raw material, chemicals, processes and additives authorized. All of these labels aim principally at sending a particular message to the consumer which feels more secure about what he buys.

I.7.2.2 Quality

Extract quality is generally determined considering the content in active compounds and the absence of denatured molecules. During an extraction process, degradation of compounds of interest may occur depending on process conditions, such as high temperature, presence of oxygen or long extraction time. This phenomenon must be avoided as far as possible since degradation products can affect the organoleptic and the nutritive properties of final extract. For example, ultrasound assisted extraction (UAE) of raw material containing lipids may result in the formation of radicals and consequently off-flavors in the extract [START_REF] Pingret | Degradation of Edible Oil during Food Processing by Ultrasound: Electron Paramagnetic Resonance, Physicochemical, and Sensory Appreciation[END_REF].

In the case of dyes, unsuitable extraction conditions (high temperature, light or presence of oxygen) may increase the kinetics of β-carotene oxidation [START_REF] Henry | Oxidative degradation kinetics of lycopene, lutein, and 9-cis and all-trans β-carotene[END_REF][START_REF] Stefanovich | Kinetics if beta-carotene degradation at temperatures typical of air drying of foods[END_REF]. Plus, at worst, degradation compounds may represent a threat for final consumer which is in direct contact with the product (ingestion or skin absorption).

I.7.2.3 Functionality

By definition, the functionality is "the quality of having a practical use". Natural extracts are considered as functional when they aim at accomplishing a particular task in the final foodstuffs or cosmetics in which they are added (coloring, antioxidant, texturing…).

Hence, the formulation step is essential to ensure the best extract performance. For example, the polarity of the extract must be compatible with the polarity of final product.

Measurement of extract functionality is quite difficult to implement routinely at industrial level, that's why natural extracts are generally standardized according to their content in active compounds. However, it must be kept in mind that composition and functionality do not always point to the same direction. Moreover, when activity and functionality are assessed, it should be recognized that results are influenced by the nature of the tests carried out, depending on whether they take place in polar systems where polar compounds are favored over less polar molecules to react since they are more soluble, hence more available for reaction.

I.7.2.4 Safety

Safety is a capital criterion in "eco-extract" definition. First of all, the extract must be exempt from any microbial contamination. To this end, extracts can be pasteurized or submitted to sterilizing filtration at the end of the process. Besides microorganisms, the most common contaminants found in natural extracts include pesticides, polycyclic aromatic hydrocarbons (PAH) and heavy metals. Most of the cases, they are transferred from contaminated soils to plant material during agricultural production. After plant extraction, according to the solvent used, such compounds are found in very high quantity in the final extract and very often beyond any quantitative limits. Actually, extraction process tends to concentrate the contaminants initially present in raw material in the final extract since these molecules are also soluble in the solvent and extracted at the same time as active compounds.

To limit or avoid this phenomenon, plant material sourcing must be well-reasoned as far as possible, for example using raw material proceeding from organic farming. Another solution is a previous step of plant material decontamination before extraction [START_REF] Cui | Removal of Trace Heavy Metals from a Natural Medicine Material by Supercritical CO 2 Chelating Extraction[END_REF] or sometimes even during the extraction using absorbent materials [START_REF] Valderrama | Sorption kinetics of polycyclic aromatic hydrocarbons removal using granular activated carbon: Intraparticle diffusion coefficients[END_REF].

I.7.2.5 Legislation

Development of extracts or "eco-extracts" cannot be performed without considering legislation aspects. Regarding the sector to which they are dedicated, extracts must be in accordance with specific legislations related. Indeed, a huge number of legal documents, regulations or directives governs the foodstuffs, cosmetics or pharmaceuticals, whether regarding their composition, their safety or their labelling.

For instance, in food processing sector, the use of additives including some natural extracts are governed by various regulations such as n°1333/2008. More specific regulations exist for particular cases as Regulation (n°1334/2008) dedicated to flavoring ingredients. The use of solvent for the production of foodstuffs and food ingredients is also regulated, particularly by Directive 2009/32/EC, which relates maximal solvent residue limits in the final foodstuffs.

Among the foodstuffs and food ingredients including some natural extracts, we can also find the category of "novel food". By definition, novel foods are foodstuffs or ingredients which were not consumed in European community before 1997. There are governed by Regulation n°258/97 from 27 January 1997. According to legislation, novel foods include:

 "Foods and food ingredients produced from genetically modified organisms (GMO), but which does not contain such compounds;

 Foods and food ingredients with a new or intentionally modified primary molecular structure;

 Foods and food ingredients consisting of or isolated from micro-organisms, fungi or algae;  Foods and food ingredients consisting of or isolated from plants and food ingredients isolated from animals, except for foods and food ingredients obtained by traditional propagating or breeding practices and having a history of safe food use;  Foods and food ingredients to which has been applied Article 3 a production process not currently used, where that process gives rise to significant changes in the composition or structure of the foods or food ingredients which affect their nutritional value, metabolism or level of undesirable substances."

As examples, phytosterols or extract of magnolia bark are included in this category of food ingredients.

Before being authorized for commercialization, the potential toxicity of such ingredients and the eventual nutritional imbalance induced by their introduction in the global diet have to be assessed by relevant institutions. Final decision rests with the European commission which, after consulting the EFSA (European Food Safety Authority), accepts or not the new ingredient as a novel food.

I.7.2.6 Life Cycle Assessment (LCA)

As last but not least requirement, an "eco-extract" must have a low environmental footprint. This parameter can be determined using a LCA approach.

LCA was born in a context of sustainability. It is a multi-criteria study aiming at quantifying the potential impacts of a product or a service during its whole life cycle, from the cradle to the grave [START_REF] Rebitzer | Life cycle assessment: Part 1: Framework, goal and scope definition, inventory analysis, and applications[END_REF]. Impacts (positive or negative) can be environmental, economic or social. The whole life cycle of a product is illustrated in A complete LCI from the cradle to the grave is often quite difficult and heavy to perform. Data are not always available. A gate to gate approach more focused on the process is sometimes adopted (Figure I-44) to facilitate the study. At industrial level, data can be collected directly in the production sites. This approach is useful particularly to compare processes in terms of environmental efficiency. However, in the case of natural extracts, it is recommended to consider also the agricultural step (plant growth and harvest before it use for extraction) and the recycling and treatment of extraction by-products [START_REF] Vian | Chapitre 1: Eco-Extraction : contexte et innovation[END_REF].

The next step after LCI is the transformation of data into impacts. For this purpose, there are various LCA software available with implemented databases. Some of them are dedicated to specific sectors of activity. We can cite for example Food'Print v-1 for agri-

Transformation into impacts

Interpretation of results

ELCD or LCA Food can be implemented by default, but it is generally possible to add the database of its choice in the program used.

Therefore, LCA software enables to convert data from LCI into impacts. Actually, depending on the program used, different types of impact can be chosen. The most common are greenhouse effect, euthrophisation, acidification, ozone depleting, eco-toxicity and fossil resources depletion. They correspond to "midpoint" impacts dedicated to scientific or advertised community. It is also possible to express the results into damages, particularly for communicating with non-advertised public. In this case, we can talk about human health, increase of cancer rate or loss of biodiversity for instance.

The mode of action of the software is very simple. The life cycle of the product is firstly separated into its different constitution blocks, in a more or less detailed way. For example, the block corresponding to the fabrication can be divided into the different operation units. Then, the contribution of each step regarding each impact is calculated using algorithms. Results can be expressed in a table or as a graphic. Besides determining the global environmental footprint of a product, it enables to see which step in the life cycle is more impacting for potential improvement. Even using MW in the process, resulting "eco-extracts" are commonly named "essential oils". However, according to REACH legislation, an essential oil is a volatile part of a natural product which can be obtained by HD and steam distillation, and more particularly by expression in the case of citruses, and extracts obtained with MW processes do not meet this definition. Hence, from a regulatory point of view, it is not convenient to name them "essential oils". Therefore, further demarches must be undertaken to define at best these new "eco-extract" (as Novel Food).

Plant material

As illustrated in

I.8 CONCLUSION

In conclusion, this chapter clearly shows that the demarche of green extraction is not limited to one type of natural extract. It is accessible for all businesses (food processing, cosmetics, pharmaceuticals…) thanks to well-defined guidelines related to each principle.

Proposed success stories testify that the adoption of such demarche is possible at laboratory and industrial levels, and provide solutions and tools for: This chapter also shows that adopting such initiative presents economical, societal and environmental advantages for industrials. Moreover, even if some points remain at the stage of research and development, it enables to apprehend potential legislation evolution regarding these aspects. This thesis, centered on process intensification using innovative technologies, solvent substitution and solvent elimination using a bio-refinery concept, fits perfectly with the issues raised in this chapter.

 Well-

II.1 PLANT MATERIALS

In this thesis, studies have been performed principally on two kinds of raw materials: rosemary leaves and ginger press cake.

Rosemary was selected because it is a strategic and historic raw material for Naturex.

This plant material can provide essential oil by hydrodistillation or extraction with supercritical CO2, and active compounds (as RA and CA) by solvent extraction.

Regarding ginger press cake, it is one of the by-products obtained after juice processing of ginger rhizomes. Since it still contains valuable products (essential oil and gingerols), we chose to valorize this raw material into high valued compounds.

II.1.2 Ginger

Ginger rhizomes (GR) and ginger press cake (GP) were provided by Naturex. GP was obtained after industrial pressing of GR. Initial moisture was 10.7 % and 25.4 % for GR and GP respectively. GR was stored at 4 °C and GP was frozen (-18 °C) before use. For analysis, water, methanol, acetonitrile, acetone, phosphoric acid 85 %, pentane 98 % and diethyl ether >99 % were analytical grade and purchased from Sigma Aldrich.

II.2.2 Reagents

Folin-Ciocalteu's phenol reagent and sodium carbonate (Na2CO3) were purchased from Emsure Merck Millipore (France)

Randomly methylated β-cyclodextrin (RMCD), Trolox ((±)-6-hydroxy-2,5,7,8tetramethylchromane-2-carboxylic acid), APPH (2,2'-azobis(2-methylpropionamidine) dihydrochloride), potassium phosphate monobasic (HPLC), potassium phosphate dibasic (PBS), 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) were from Sigma-Aldrich (France).

II.2.3 Standards

RA (97 %) and CA (98 %) standards were from Sigma-Aldrich (France). The Conductor-like Screening Model for Real Solvents (COSMO-RS) is a method for molecular description and solvent screening based on a combination of quantum chemistry (COSMO) and statistical thermodynamics (RS) to determine and predict thermodynamic properties without experimental data [START_REF] Klamt | Prediction of the mutual solubilities of hydrocarbons and water with COSMO-RS[END_REF].

COSMO-RS is a two-step procedure: microscopic and macroscopic steps.

(i) First, the COSMO model is applied to simulate a virtual conductor environment for the molecule of interest which is then embedded into a virtual conductor. In such an environment, the molecule induces a polarization charge density σ on the interface between the molecule and the conductor, (i.e. on the molecular surface). During the quantum calculation through self-consistency algorithm, the solute molecule converged to its energetically optimal state in the conductor with respect to electron density and geometry. In this study, the standard quantum chemical method for the COSMO-RS approach is the density functional theory (DFT) at the B88-PW86 level with a triple zeta valence polarized basis set (TZVP). ). In all cases, extraction was performed at ebullition temperature using a solid/liquid ratio of 1/20 (m/v). After extraction, the plant matrix was removed by filtration to vacuum (n°4 filter, Auchan, France) and rinsed with 100 mL solvent. Then, the extract was concentrated until dryness using a rotary evaporator (Laborota 4001, Heidolph, Germany).

The dried extract was stored at -18 °C until used. Each experiment was performed in triplicate.

For the intensification study, the same experimental conditions were applied to rosemary leaves for 30 min or 5 h, using 90:10 (v/v) ethanol:water mixture as extraction solvent. This process was thereafter compared with alternative ones. To evaluate a potential effect of a fine dispersion in the solvent prior to extraction, they were as well applied to rosemary leaves previously ground into the solvent during 3 min with a homogenizer (Ika T25 digital Ultra-Turrax, Germany). Each experiment was performed in triplicate.

II.4.1.2 Maceration procedures

In this thesis, maceration was used as a conventional process for the extraction of RA, CA and UA from rosemary. Maceration was also performed as reference process to drain ginger material from its valuable phenolics.

II.4.1.2.1 Application to rosemary leaves

Rosemary leaves were submitted to conventional maceration (CM) in double jacket reactor during 30 min with ethanol:water 90:10 (v/v) as extraction solvent. The solid/liquid ratio was 1/20 (m/v) to limit the saturation of the solvent. Extraction temperature was maintained at 40 °C using a cryostat (Ministat 125, Huber, Germany). Matrix was homogenized into the solvent with a motorised stirrer (Ika Labortechnik RW16 basis, Germany). After extraction, the solvent was separated from the matrix by filtration to vacuum using a filter paper. The extract was concentrated until dryness by solvent evaporation under vacuum (Laborota 4001, Heidolph, Germany). Each experiment was performed in triplicate.

II.4.1.2.2 Application to ginger plant materials

GR, GP and GPMHG were submitted to CM followed by HPLC-DAD analysis to determine the available gingerols and 6-shogaol content in each. For all characterizations, plant materials (GR, GP and GPMHG) were previously freeze-dried and ground below 3 mm.

Phenolics extraction was performed according to the procedure described by Mukherjee et al. extraction. 1 kg of GP was submitted to HD using a Clevenger-type apparatus [START_REF] Mnayer | Simultaneous Extraction of Essential Oils and Flavonoids from Onions Using Turbo Extraction-Distillation[END_REF].

Extraction was performed with 4 L of water for 360 min until no more EO was obtained.

Then EO was recovered and stored at 4 °C before analysis.

II.4.2 Alternative processes

Six alternative extraction processes were performed to extract RA, CA and UA from rosemary: ultrasound (US) bath, US reactor, US probe, reflux under microwaves (MW), MW under nitrogen pressure and MW under vapor pressure. Those processes are illustrated in

II.4.2.1.2 Ultrasound reactor

Ground rosemary leaves were immersed into the solvent and submitted to US during 30 min using an US reactor (150 W, Pex1, REUS, France). Matrix was homogenized into the solvent with a motorised stirrer (Ika Labortechnik RW16 basis, Germany). Extraction temperature was kept constant at 40 ± 1 °C using a cooling system (Ministat 125, Huber, Germany) connected to the double jacket of the reactor. Each experiment was performed in triplicate.

II.4.2.1.3 Ultrasound probe

Rosemary leaves were placed in a double jacket reactor with the solvent and the whole was submitted to US (1 kW, UIP 1000 hdT, Hielscher Ultrasonics GmbH, Germany) during 30 min. US were applied to the system using a sonotrode immerged in the solvent approximately 2 cm. Extraction temperature was measured with an external sensor and controlled at 40 ± 1 °C with a cryostat (Ministat 125, Huber, Germany). Each experiment was performed in triplicate.

II.4.2.2 Microwave assisted extraction (MAE) of active compounds from rosemary leaves

II.4.2.2.1 Microwave assisted extraction under pressure (nitrogen pressure)

Rosemary leaves were packaged in gauze in order to be totally immersed in the solvent. The whole was placed in a reactor. Aiming at temperature homogeneity, the reactor was immersed in 700 mL of distilled water and introduced in the MW cavity. Extraction was performed using a high performance MW reactor (1,2 kW, UltraClave, Milestone, Italy).

Before starting extraction, oxygen in the apparatus was flushed using a nitrogen flow.

Pressure was reached using a nitrogen flow and temperature was reached with a MW heating.

Extraction temperature was set at 70 °C and initial pressure at 100 bar. Pressure and temperature were controlled by external sensors. At the set temperature, extraction was performed during 30 min. MW power was not fixed, it varied as a function of temperature, firstly to reach the set temperature and then to keep it constant during the extraction step.

Each experiment was performed in triplicate.

II.4.2.2.2 Microwave assisted extraction

Rosemary leaves were immersed into the solvent and submitted to MW during 30 min, using a MW reactor (900 W, EOS-GR, Milestone, Italy) and a reflux apparatus. MW power was fixed at 210 W (1 W/g). Extraction was done at boiling temperature (78 °C) and atmospheric pressure. Each experiment was performed in triplicate.

II.4.2.2.3 Microwave assisted extraction under pressure (vapor pressure)

Rosemary leaves were packaged in gauze in order to be totally immersed in the solvent, and placed in a closed Teflon reactor. The whole was introduced in a MW reactor (1 kW, Ethos 1, Milestone, Italy) and heated using MW until the fixed temperature.

Extraction was done at 125 °C and at 150 °C during 30 min. MW power was fixed at 300 W but it varied depending on temperature, firstly to reach the set temperature and then to keep it constant during the extraction step. Temperature and pressure were measured with external sensors. Each experiment was performed in triplicate.

II.4.3 Bio-refinery-inspired processes

In this thesis, two processes inspired from the bio-refinery concept were developed to valorize completely rosemary and ginger by-products. Both designed processes are presented in this section.

II.4.3.1 Towards a bio-refinery of rosemary leaves

The process developed is presented in Figure II-5. This process aims at extracting consecutively RA and CA from rosemary in a single process. mass balance between the amount of ethanol engaged as solvent and the amount of ethanol recovered in F2). The whole was submitted to a third reflux for 60 min with mechanical stirring. After this third extraction, the plant matrix R3 was removed by filtration to vacuum (retention rate 35-15 µm) and the filtrate F3 (rich in RA) was stored at 4 °C. After determination of dry matter, F1, F2 and F3 were injected in the HPLC system to determine their content in CA (F1) and RA (F2 and F3).

II.4.3.2 Towards a bio-refinery of ginger by-products

A bio-refinery concept was developed for total valorization of ginger by-products. The aim of this bio-refinery was the recovery of several high valued compounds at the end of each consecutive step, without addition of any external solvent or water. The "dry" bio-refinery

(DBR) pattern is illustrated in Figure II-6.
As described in the flow sheet, after pressing, GP was firstly submitted to microwave hydrodiffusion and gravity (MHG), followed by UAE. To characterize ginger by-products and to assess the performance of DBR, conventional processes (HD and maceration) were

II.4.3.2.1 Microwave Hydrodiffusion and Gravity apparatus and procedure

For each experiment using MHG, 500 g of GP were treated. Principle and apparatus are described in previous studies [START_REF] Zill-E-Huma | A novel idea in food extraction field: Study of vacuum microwave hydrodiffusion technique for by-products extraction[END_REF][START_REF] Zill-E-Huma | Clean recovery of antioxidant flavonoids from onions: Optimising solvent free microwave extraction method[END_REF] and in section I.3.3.1. Extraction was performed in a MW laboratory oven (900 W, EOS-GR Microwave Gravity Station, Milestone, Italy) at atmospheric pressure. MW power delivered to GP was varied between 0.6 W/g and 1.8 W/g. Germany) for 90 min. UI in W/cm 2 and PD in W/cm 3 were both considered to evaluate the ultrasonic power since literature shows that they were both adapted for such type of extraction [START_REF] Paniwnyk | The enhancement and scale up of the extraction of anti-oxidants from Rosmarinus officinalis using ultrasound[END_REF][START_REF] Suslick | The effects of ultrasound on nickel and copper powders[END_REF][START_REF] Vinatoru | The use of ultrasound for the extraction of bioactive principles from plant materials[END_REF][START_REF] Vinatoru | Ultrasonically assisted extraction (UAE) of natural products some guidelines for good practice and reporting[END_REF]. Moreover, the use of W/cm 3 as unit is more appropriated whether further pilot and industrial up-scaling are envisaged. A range of ultrasonic amplitude was tested: 25 %, 50 %, 75 % and 100 %, corresponding to an UI (and the corresponding PD) of 4.4 W/cm 2 (0.080 W/cm 3 ), 9.4 W/cm 2 (0.170 W/cm 3 ), 13.4 W/cm 2 (0.242 W/cm 3 ) and 16.7 W/cm 2 (0.303 W/cm 3 ) respectively. UI (W/cm 2 ) was calculated according to the equation described by Pingret et al. [START_REF] Pingret | Lab and pilot-scale ultrasound-assisted water extraction of polyphenols from apple pomace[END_REF]. US were applied to the system using a sonotrode immerged in the solvent. Temperature was maintained at 50 ± 5 °C with a cryostat (Alpha RA8, Lauda, Germany) and monitored with an external thermocouple. Plant material was homogenized in the solvent during UAE at 250 rpm with a magnetic stirrer (IKA RCT basic, VWR, France).

Liquid samples were collected during the experiment (approximately 2 mL) and filtered on cotton before drying in oven at 100 °C to determine dry matter content.

After extraction, remaining solvent enriched with the extract was separated from the plant material residue by centrifugation at 4000 rpm for 20 min (Himac CT6E, VWR by Hitachi Koki Co., Ltd., USA) and filtration under vacuum using a filter paper. Extract was recovered from filtrate by solvent evaporation under vacuum. The extract was stored at 4 °C before analysis. Each experiment was performed in duplicate. For assessment of UAE effect on extraction, a CM was performed by mechanical stirring using identical extraction conditions as UAE. (i) For RA, the column was a C18 (5 µm, 4.6 mm x 250 mm, Zorbax SB, Agilent Technologies, France); the mobile phase (isocratic mode) was composed of 68 % water with 0.1 % TFA and 32 % acetonitrile (v/v) and the flow rate was set at 1 mL/min; the column oven temperature was set at 20 °C and the run time was 10 min. 5 µL were injected. RA was detected at 328 nm.

(ii) For CA, the column was a C18 (1.8 µm, 4.6 mm x 50 mm, Zorbax Eclipse XBD-C18, Agilent Technologies, France); the mobile phase (isocratic mode) was composed of 65 % acetonitrile and 35 % water with 0.5 % H3PO4 (v/v), and the flow rate was set at 1.5 mL/min; the column oven temperature was set at 25 °C. 5 µL were injected. CA was detected at 230 nm.

(iii) For UA, the column was a C18 (3 µm, 4 mm x 150 mm, All C18, Agilent Technologies, France); the mobile phase (isocratic mode) was composed of 90 % acetonitrile and 10 % water with 0.1 % H3PO4 (v/v) and the flow rate was set at 0.6 mL/min; the column oven temperature was set at 30 °C. Run time was 15 min. 5 µL were injected. Detection was performed at 210 nm. TPC of a plant extract is generally determined using the non-competitive Folin-Ciocalteu method. It is based on the reduction of Folin-Ciocalteu reagent (composed of hexavalent phosphomolybdic/phosphotungstic acid complexes [START_REF] Peterson ; Rosebrough | Review of the Folin phenol protein quantitation method of Lowry[END_REF]) by phenolic compounds. The reaction forms a blue chromophore constituted by a phosphotungsticphosphomolybdenum complex where the maximum absorption of the chromophores (λmax = 760 nm) depends on the alkaline solution (that's why Na2CO3 is added during experiment) and the concentration of phenolic compounds [START_REF] Blainski | Application and Analysis of the Folin Ciocalteu Method for the Determination of the Total Phenolic Content from Limonium Brasiliense L[END_REF].

Folin-Ciocalteu method is generally admitted to determine TPC is an extract, but in practice, it is not absolutely right. Actually, this method is not specific to phenolic compounds and any reducing species (including phenolic compounds) can react with the reagent. It is therefore the global reducing activity which is determined. Contribution of phenolic compounds can be more or less important depending on the extract.

II.5.3.2 Experimental protocol

TPC in rosemary extracts was determined by Folin-Ciocalteu method [START_REF] Singleton | Colorimetry of Total Phenolics with Phosphomolybdic-Phosphotungstic Acid Reagents[END_REF][START_REF] Singleton | Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent[END_REF] with some modifications. Briefly, 50 µL of sample previously filtered on 0.45 µm were mixed with 1250 µL of a 5-fold diluted Folin-Ciocalteu's reagent into water. The solutions were mixed thoroughly and incubated at room temperature (22 °C) for 1 min. Then 1 mL of 10 % sodium carbonate (Na2CO3) solution was added and the solutions were mixed thoroughly again.

Solutions were incubated at room temperature (22 °C) for 30 min sheltered from light.

Absorbances were measured at 760 nm using an UV-vis spectrophotometer (UV-1800, Shimadzu, Japan). Standardization curves were performed with RA and CA solutions at different concentrations. The TPC was expressed as mg of RA equivalent/ gram of extract powder on dry weight basis. The data were presented as the mean of duplicate analysis. Eq. II-1.

FL-H + ROO

•  FL • + ROOH (k1)
Eq. II-2. This method is non-competitive and consists in the quenching of this free radical by an anti-radical (A). This phenomenon occurred either by transfer of electron from the anti-radical agent to DPPH • to generate DPPH -which will capture afterwards a proton in the system (Eq. II-4); or directly by transfer of an hydrogen atom to generate DPPH-H molecule (Eq. II-5) [START_REF] Laguerre | Bases moléculaires de la capacité antioxydante de composés phénoliques : étude en milieux homogène, émulsionné et cellulaire[END_REF]. It results in the discoloration of the reaction media (from purple to yellow) according to the amount of reacted DPPH • .

A-H + ROO

•  A • + ROOH (k2)
Eq. II-4.

A-H 

A -+ H + A -+ DPPH •  A • + DPPH - DPPH -+ H +  DPPH-H
Eq. II-5.

AH + DPPH

•  A • + DPPH-H II.5.5.

Experimental protocol

Free radical scavenging activity of each extract was determined using DPPH free radical. The method, consisting in the reduction of DPPH free radicals by antioxidants contained in the extract, was based on Brand-Williams et al. procedure [START_REF] Brand-Williams | Use of a free radical method to evaluate antioxidant activity[END_REF]. Briefly, 25 mg of DPPH were solubilized into 100 mL methanol, then diluted 1:10 with methanol to reach 0.025 g/L. Different solutions of rosemary extract were prepared at several concentrations with methanol: 0.1875, 0.375, 0.75, and 1.5 g/L. One hundred µL of sample were thoroughly mixed with 3.9 mL DPPH solution, and incubated at 22 °C for 30 min sheltered from light.

Concentrations of extract in final solutions were 4.69, 9.38, 18.75 and 37.5 mg/L, and that of DPPH was 0.024 g/L (61 µM).

Then, absorbance of the reaction mixtures was measured at 518 nm using a UV-Vis spectrophotometer (UV-1800, Shimadzu, Japan). The absorbance were converted into percentage of antioxidant activity (%AA) according to the following equation:

Eq. II-6.

%AA = 100 -(

Abs sample-Abs blank Abs reference ×100)

Where Abssample is the absorbance of the sample at a given concentration, Absblank is the absorbance of the pure solvent (methanol) and Absreference is the absorbance of the DPPH solution without any extract.

The IC50 was determined using the equation of the linear curves obtained for all extract concentrations that corresponds to the extract concentration which shows a % AA of 50 % (extract concentration necessary to scavenge 50 % of DPPH). RA was considered as reference, therefore the DPPH scavenging capacity of the extract was expressed in g RA equivalent/g extract.

II.6 CALCULATIONS

In this manuscript, results are expressed in different ways, corresponding to:

Eq. II-7.

Extraction yield (%) = ( weight of extract (DW) weight of initial raw material (DW) ×100)

Eq. II-8.

Purity (%) = (

weight of compound (DW) weight of extract (DW) ×100)

Eq. II-9.

Content in active (mg/g) = (purity × weight of extract (mg) weight of initial raw material (g) )

Eq. II-10.

Active recovery (%) = (

weight of compound extracted (DW) weight of compound available (DW) ×100)

In the process intensification study (CHAPTER III), estimation of specific carbon emissions resulting from electric consumption was determined considering that 1 kWh = 800 g CO2 [START_REF] Li | Solvent-free microwave extraction of bioactive compounds provides a tool for green analytical chemistry[END_REF]. Energy consumption of each process was measured using an electrical meter (Cost Control, La Crosse Technology, France).

ULTRASOUND VERSUS MICROWAVE AS GREEN PROCESSES

III.1 INTRODUCTION

The growing demand for natural products leads to constant developments of natural extracts. In the field of food preservation, compounds such as tocopherols and flavonoids are broadly used as antioxidants [START_REF] Brewer | Natural Antioxidants: Sources, Compounds, Mechanisms of Action, and Potential Applications[END_REF]. Natural antioxidants are extracted from plants, more specifically from herbs or spices, where numerous compounds have been identified as potential antioxidants such as vitamins, lipids, and predominantly polyphenols [START_REF] Brewer | Natural Antioxidants: Sources, Compounds, Mechanisms of Action, and Potential Applications[END_REF]. Due to its polyphenol composition, rosemary can be considered as a reference matrix for the production of natural antioxidant extracts [START_REF] Brewer | Natural Antioxidants: Sources, Compounds, Mechanisms of Action, and Potential Applications[END_REF][START_REF] Yanishlieva | Natural antioxidants from herbs and spices[END_REF].

Rosemary (Rosmarinus officinalis L.) is native to the Mediterranean region. Rosemary belongs to the Lamiaceae family and possesses needle-like leaves which contain a powerful fragrance and polyphenolic compounds: phenolic acids such as rosmarinic acid (RA) and caffeic acid; phenolic diterpenes such as carnosic acid (CA), carnosol (CO) and triterpenoids such as ursolic acid (UA) (Figure III-1). This polyphenol profile induces antioxidant [START_REF] Erkan | Antioxidant activities of rosemary (Rosmarinus Officinalis L.) extract, blackseed (Nigella sativa L.) essential oil, carnosic acid, rosmarinic acid and sesamol[END_REF][START_REF] Frankel | Antioxidant activity of a rosemary extract and its constituents, carnosic acid, carnosol, and rosmarinic acid, in bulk oil and oil-inwater emulsion[END_REF][START_REF] Moreno | Antioxidant and antimicrobial activities of rosemary extracts linked to their polyphenol composition[END_REF], antibacterial [START_REF] Moreno | Antioxidant and antimicrobial activities of rosemary extracts linked to their polyphenol composition[END_REF][START_REF] Ojeda-Sana | New insights into antibacterial and antioxidant activities of rosemary essential oils and their main components[END_REF] and antimutagenic properties to rosemary extracts. RA and CA are more specifically used in the food industry as natural antioxidants [START_REF] Ortuño | Shelf life of meat from lambs given essential oil-free rosemary extract containing carnosic acid plus carnosol at 200 or 400mgkg-1[END_REF][START_REF] Serrano | Use of dietary rosemary extract in ewe and lamb to extend the shelf life of raw and cooked meat[END_REF]. Apart from the antioxidant properties of rosemary compounds, UA is another valuable natural compound which is studied for its pharmacological effects (e.g. antitumor property [START_REF] Liu | Pharmacology of oleanolic acid and ursolic acid[END_REF]). Throughout literature, at a laboratory scale, extraction of RA and CA from rosemary leaves has been investigated using different technologies: conventional solvent extraction (CSE) [START_REF] Meziane-Assami | Geographical Differentiation of Rosemary Based on GC/MS and Fast HPLC Analyses[END_REF], microwave (MW) [START_REF] Rodríguez-Rojo | Assisted extraction of rosemary antioxidants with green solvents[END_REF][START_REF] Sui | Microwave irradiation to pretreat rosemary (Rosmarinus officinalis L.) for maintaining antioxidant content during storage and to extract essential oil simultaneously[END_REF], ultrasound assisted extraction (UAE) [START_REF] Tena | Supercritical Fluid Extraction of Natural Antioxidants from Rosemary: Comparison with Liquid Solvent Sonication[END_REF][START_REF] Rodríguez-Rojo | Assisted extraction of rosemary antioxidants with green solvents[END_REF][START_REF] Mulinacci | Storage method, drying processes and extraction procedures strongly affect the phenolic fraction of rosemary leaves: An HPLC/DAD/MS study[END_REF][START_REF] Albu | Potential for the use of ultrasound in the extraction of antioxidants from Rosmarinus officinalis for the food and pharmaceutical industry[END_REF][START_REF] Bicchi | Determination of phenolic diterpene antioxidants in rosemary (Rosmarinus officinalis L.) with different methods of extraction and analysis[END_REF], supercritical and subcritical fluid extraction [START_REF] Herrero | Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review[END_REF][START_REF] Genena | Rosemary (Rosmarinus officinalis): a study of the composition, antioxidant and antimicrobial activities of extracts obtained with supercritical carbon dioxide[END_REF][START_REF] Tena | Supercritical Fluid Extraction of Natural Antioxidants from Rosemary: Comparison with Liquid Solvent Sonication[END_REF], pressurized liquid extraction (PLE) [START_REF] Herrero | Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review[END_REF]203], deodorization by Instant Controlled Pressure drop [START_REF] Allaf | Deodorization by instant controlled pressure drop autovaporization of rosemary leaves prior to solvent extraction of antioxidants[END_REF] or extraction with ionic liquids (IL) [START_REF] Zu | Ultrasound-Assisted Extraction of Carnosic Acid and Rosmarinic Acid Using Ionic Liquid Solution from Rosmarinus officinalis[END_REF]. Table III- Due to their chemical structure, CA and RA are conventionally extracted by methanol and acetone [START_REF] Bicchi | Determination of phenolic diterpene antioxidants in rosemary (Rosmarinus officinalis L.) with different methods of extraction and analysis[END_REF][START_REF] Durling | Extraction of phenolics and essential oil from dried sage (Salvia officinalis) using ethanolwater mixtures[END_REF][START_REF] Suhaj | Spice antioxidants isolation and their antiradical activity: a review[END_REF]. Other solvents have been used such as ethanol and water or a mixture of both [START_REF] Durling | Extraction of phenolics and essential oil from dried sage (Salvia officinalis) using ethanolwater mixtures[END_REF]. Considering sustainable and safe extraction, there is a major interest in the use of a mixture of ethanol and water as an extraction solvent, each of these solvents being classified as GRAS solvents.

Aiming at intensification of extraction taking into account concept of "Green

Chemistry", a comparative study is carried out between ultrasound (US) and MW to extract water extraction [START_REF] Ibañez | Subcritical Water Extraction of Antioxidant Compounds from Rosemary Plants[END_REF][START_REF] Herrero | Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review[END_REF]) while others report a degradation with mild temperatures in stability studies (40 °C or less; [START_REF] Okamura | High-performance liquid chromatographic determination of carnosic acid and carnosol in Rosmarinus officinalis and Salvia officinalis[END_REF][START_REF] Zhang | Degradation Study of Carnosic Acid, Carnosol, Rosmarinic Acid, and Rosemary Extract ( Rosmarinus officinalis L.) Assessed Using HPLC[END_REF]). Overall, it seems that temperature is not the sole authors [START_REF] Zhang | Degradation Study of Carnosic Acid, Carnosol, Rosmarinic Acid, and Rosemary Extract ( Rosmarinus officinalis L.) Assessed Using HPLC[END_REF][START_REF] Schwarz | Antioxidative constituents of Rosmarinus officinalis and Salvia officinalis. I. Determination of phenolic diterpenes with antioxidative activity amongst tocochromanols using HPLC[END_REF]. Additionally, CO also has antioxidant properties [START_REF] Johnson | Carnosol: A promising anti-cancer and anti-inflammatory agent[END_REF][START_REF] Jordán | Relevance of the carnosic acid/carnosol ratio for the level of rosemary diterpene transfer and for improving lamb meat antioxidant status[END_REF]. In order to assess if CA was converted into CO during extraction, we examined the purities of CA and CO in the extracts (Table III [START_REF] Cuvelier | Antioxidant Constituents in Sage (Salvia officinalis)[END_REF], 7-methy, l-epirosmanol [START_REF] Schwarz | Antioxidative constituents of Rosmarinus officinalis and Salvia officinalis. I. Determination of phenolic diterpenes with antioxidative activity amongst tocochromanols using HPLC[END_REF] and probably rosmanol 9-ethyl ether [START_REF] Djarmati | High antioxidant activity of extracts obtained from sage by supercritical co2 extraction[END_REF]. Other degradation products of CA such as rosmanol and rosmaridiphenol are also generated from CA during process. Moreover, it has to be underlined that CO naturally occurs in rosemary leaves [START_REF] Frankel | Antioxidant activity of a rosemary extract and its constituents, carnosic acid, carnosol, and rosmarinic acid, in bulk oil and oil-inwater emulsion[END_REF], which could explain the concentration of CO found at lower extraction temperatures (Table III Beyond the alternative solvents available for natural products extraction, hydroalcoholic mixtures are good candidates since they are rather few selective and scanned a wide range of polarities regarding the compounds to be extracted. Surprisingly, most extractions using hydro-alcoholic mixtures are performed by default with high amount of ethanol (between 70 and 90 % ethanol) [START_REF] Bobinaitė | Extraction of phenolic compounds from raspberry press cake[END_REF][START_REF] Galanakis | Recovery and preservation of phenols from olive waste in ethanolic extracts[END_REF][START_REF] Adham | Comparative extraction methods, phytochemical constituents, fluorescence analysis and HPLC validation of rosmarinic acid content in Mentha piperita, Mentha longifolia and Osimum basilicum[END_REF][START_REF] Jacotet-Navarro | Ultrasound versus microwave as green processes for extraction of rosmarinic, carnosic and ursolic acids from rosemary[END_REF]. This is particularly exemplified with rosemary extracts which are currently used as antioxidants in the food sector. At the industrial level, oil soluble rosemary extracts are obtained via an extraction using liquid solvents or supercritical carbon dioxide. Generally, acetone [START_REF] Ban | Antioxidant activities from different rosemary clonal lines[END_REF], pure ethanol or hydro-alcoholic mixtures with high content in ethanol (80 % to 100 %) are selected to extract both carnosic (CA) and rosmarinic (RA) acids [START_REF] Liu | Application of ionic liquids based microwave-assisted simultaneous extraction of carnosic acid, rosmarinic acid and essential oil from Rosmarinus officinalis[END_REF][START_REF] Albu | Potential for the use of ultrasound in the extraction of antioxidants from Rosmarinus officinalis for the food and pharmaceutical industry[END_REF][START_REF] Rodríguez-Rojo | Assisted extraction of rosemary antioxidants with green solvents[END_REF][START_REF] Sui | Microwave irradiation to pretreat rosemary (Rosmarinus officinalis L.) for maintaining antioxidant content during storage and to extract essential oil simultaneously[END_REF][START_REF] Allaf | Deodorization by instant controlled pressure drop autovaporization of rosemary leaves prior to solvent extraction of antioxidants[END_REF][START_REF] Jacotet-Navarro | Ultrasound versus microwave as green processes for extraction of rosmarinic, carnosic and ursolic acids from rosemary[END_REF][START_REF] Bellumori | Selective recovery of rosmarinic and carnosic acids from rosemary leaves under ultrasound-and microwave-assisted extraction procedures[END_REF]. These molecules are known as the main antioxidants in rosemary [START_REF] Frankel | Antioxidant activity of a rosemary extract and its constituents, carnosic acid, carnosol, and rosmarinic acid, in bulk oil and oil-inwater emulsion[END_REF] and are of special interest due to a strong market demand.

Apart from Oliveira et al., who optimized the ethanol content to extract RA, CA and carnosol (CO) from rosemary [START_REF] Liadakis | Multiresponse optimization of an extraction procedure of carnosol and rosmarinic and carnosic acids from rosemary[END_REF], very few studies were carried out to rationalize the ethanol:water mixture. Furthermore, the resulting extracts are generally characterized by their content in active compounds using HPLC, for reasons of simplicity and speed of analysis. Their global activity (antioxidant, antimicrobial…) in food formulations or in cells can be evaluated as well, but both profile and activity characterizations are scarcely performed for the same extract. This raises the question of which methodology should be adopted to determine the best solvent for extraction. Should industrials focus on solubility, profile, or activity? Is there a common solvent to maximize these three responses?

The present study addresses two important aspects. The first one is about a better understanding of solubilization and extraction phenomenon. It is implemented for the case of rosemary and more particularly its antioxidants (RA and CA). To this end, solvent effects were not only evaluated in terms of global mass extraction yield, total phenolic content (TPC) (through their reducing capacity), and specific RA and CA composition, but also in terms of free radical scavenging (DPPH method) and antioxidant (ORAC method) activities of final extracts. Theoretical comprehension of dissolving mechanisms was performed using the COSMO-RS (Conductor like screening model for real solvents) approach and was compared with experimental solubilities of targeted compounds measured in various ethanol:water mixtures. The procedure is summarized in Figure IV-1.

In a second part, based on the previous results, a process inspired from the bio-refinery concept was developed to extract separately and consecutively both RA and CA from rosemary with hydro-alcoholic mixtures. When it comes to the extraction process of specific compounds from a plant material, the solvent choice is crucial. It is current belief that a solvent which solubilizes a compound would be a good phase for its extraction. Hence, a coarse screen to sift good extraction solvents from thousands of possibilities is usually to consider the following concepts:

(i) "like dissolves like" is a general principle (i.e. two molecules or solvents having similar polarity are soluble or miscible) (ii) solubility is higher when the temperature of the system increases;

(iii) the higher the molecular weight of a solute, the lower its solubility in a given solvent;

(iv) extraction is predominantly determined by solubility phenomena Today, prediction tools are available to evaluate the solubilizing capacities of several solvents. For example, COSMO-RS software is increasingly used in the field of extraction [START_REF] Sicaire | Alternative Bio-Based Solvents for Extraction of Fat and Oils: Solubility Prediction, Global Yield, Extraction Kinetics, Chemical Composition and Cost of Manufacturing[END_REF][START_REF] Sicaire | Experimental approach versus COSMO-RS assisted solvent screening for predicting the solubility of rapeseed oil[END_REF][START_REF] Yara-Varón | Is it possible to substitute hexane with green solvents for extraction of carotenoids? A theoretical versus experimental solubility study[END_REF] since it enables to classify solvents against each other on the basis of how well they can solubilize a compound of interest. The predictions can be confirmed afterwards by experiments.

IV.3.1.1 Theoretical solubilities: COSMO-RS simulations

Solvent selection is usually based on polarity-based solubility parameters between targeted compounds and solvents. In contrast to standard quantum chemistry which considers molecules in vacuum, COSMO-RS calculations are done in a virtual conductor embedding the molecules. Calculations provide the conductor-polarization charge density σ on the surface of the molecules, which turns out to be a good descriptor of the local surface polarity. The σsurface-that is the molecular surface color-coded by σ-and the σ-profile-that is the histograms of the molecular surface with respect to the surface polarity σ-describe similarities and differences between RA, CA, ethanol, and water. From these data, relative solubilities of RA and CA in several ethanol:water mixtures were determined. Predicted values were compared with experimental data obtained in the previous part. Note that the same trend was observed with COSMO-RS predictions when boiling points of the mixtures were considered for calculation. Regarding the pH of the extraction medium (~ 6-7), RA and CA are mostly under their deprotonated form (i.e. conjugated bases), since their pKa in pure water is 2.9 and 4.0, respectively (ACD-Lab data). However, for sake of convenience and because we do not have access to their pKa in all mixtures, we only considered the protonated form. In the previous work of Filly et al. [START_REF] Filly | Alternative solvents for extraction of food aromas. Experimental and COSMO-RS study[END_REF], this aspect was not developed since the solutes were aromas not encompassing any carboxylic acid. Schröder et al. predicted the aqueous solubilities of carboxylic acids with COSMO-RS neglecting the effect of COOH dissociation [START_REF] Schröder | Prediction of aqueous solubilities of solid carboxylic acids with COSMO-RS[END_REF]. In our case, RA and CA were considered as solid solutes and the relative solubilities of each compound in ethanol:water mixtures were determined (ratios were transformed from vol:vol to mol:mol). The best solubilizing solvent was found to be 100 % ethanol in all cases When results are expressed as g molecule/100 g extract, it appeared that purity of RA slightly rose from 0 to 30 % ethanol. Beyond this threshold (30 %), a decrease of RA content is observed with a dramatic collapse after 80 % ethanol. Therefore, increasing the proportion of ethanol beyond 30 % contributes to a severe decrease of selectivity for RA ( IV-1, that the more the ethanol content in the hydro-alcoholic mixture, the more stable is CA. Thus, the increase in CA purity with increasing ethanol seems to be due not only to a better solubility but also to a better stability in ethanol than water. It stems from the above, that the best solubilizing phase (100 % ethanol) is not the best extraction solvent, especially when we look at the RA purity. This results suggests that solubilization is not the predominant process that drives the extraction and that other important phenomena must be taken into consideration. A closer look at the definition of "plant extraction" brings a sequential molecular process roughly divided in three steps:  diffusion of the solvent through the plant material core  desorption of the targeted compound from the plant matrix due to chemical affinity with the solvent  and mass transfer of the solute from the plant vicinity to the solvent bulk.

(Figure IV-2).
We should first mention that the solubility of the solute in the solvent does not impact the diffusion of this latter through the plant matrix. Consequently, it is not surprising that solubility-either given by an experimental protocol or by COSMO-RS calculations-is a poor descriptor of the overall extraction performances. Besides the solvent capacity to solubilize a solute, the mass transport phenomena determined by the complex interactions occurring between the plant material and the solvent, and between the plant material and the molecule to extract, must be considered when extraction is performed. In other words, if the "like dissolves like" principle is experimentally verified by comparing COSMO-RS and experimental solubilities, it cannot be extrapolated to any "like extracts like" principle.

Another parameters which must be taken into account to explain the difference between solubilization and extraction is the temperature. Indeed, both theoretical (COSMO-RS) and experimental solubility values were determined at ambient temperature, whereas extractions were performed at boiling point.

Regarding selectivity of extraction (corresponding to the purity and expressed in g molecule/100 g extract), the result for CA is in accordance with predicted and experimental data (100 % ethanol in all three cases) (Figure IV-4 (c)). CA is suspected to be mainly located in the trichromes of rosemary leaves [START_REF] Birtić | Carnosic acid[END_REF][START_REF] Brückner | Characterization of two genes for the biosynthesis of abietane-type diterpenes in rosemary (Rosmarinus officinalis) glandular trichomes[END_REF], suggesting that the molecule is easily accessible for extraction with 100 % ethanol in which it is most soluble. In contrast, for RA, the theoretical and experimental solubilities (100 % ethanol) were not correlated with purity values (30 % ethanol) (Figure IV-4 (c)) which can be tentatively explained by the histolocalisation of RA into the rosemary leaves. Like most of polyphenols, RA mainly accumulates in the vacuole of plant cells [START_REF] Pinelo | Upgrading of grape skins: Significance of plant cell-wall structural components and extraction techniques for phenol release[END_REF][START_REF] Petersen | Rosmarinic acid: new aspects[END_REF]. Crossing several cell compartments such as walls and membranes to get to the vacuole may be particularly difficult for pure ethanol compared to water:ethanol mixtures. Unlike these latters, ethanol may indeed denaturate proteins that will eventually form a physical barrier hindering the solvent access to vacuolar polyphenols [START_REF] Chen | Optimization of extraction of phenolics from leaves of Ficus virens[END_REF]. reactivity standpoint, RA should exhibit higher reducing activity than CA. It could also be supposed that CA is poorly soluble in the test system since the reduction of Folin-Ciocalteu reagent takes place in water. Despite CA standard was prepared in ethanolic stock solution, once in the water, it is not necessarily well-solubilized. It is possible that a significant part of CA (the insoluble part) self-aggregates to form association colloids in water, hindering its homogeneous distribution throughout the system, hence preventing an optimal reduction of the reagent, contrary to RA for which the aqueous phase is optimal. The solubility issues of antioxidants has already been mentioned by Laguerre et al. who postulated in a series of articles that the physical chemical environment of a molecule significantly modulates its reducing potential [START_REF] Laguerre | How to boost antioxidants by lipophilization?[END_REF][START_REF] Laguerre | What Makes Good Antioxidants in Lipid-Based Systems? The Next Theories Beyond the Polar Paradox[END_REF].

Figure IV-5 (a)
shows that the highest TPC was obtained for 30 % ethanol. This ratio is different from the ones which were selected considering solubility (100 % ethanol) and extraction yields (50-80 % ethanol). However, as shown in Figure 4b, the highest yield for RA purity in the extract was obtained for the same ethanol:water ratio (30 % ethanol). Since RA is a better reducer than CA, it is logical to consider that TPC evolution parallels the RA amount into the extract. This can be seen when comparing the trends of RA purity ( Antioxidant activity of pure RA and CA were evaluated using hydro-ORAC protocol. RA appears to be 6.6 times better than CA as antioxidant (Figure IV-5 (b), insert) which can be due to the hydrophilic nature of the system wherein reactions take place. Indeed, RA is much more soluble (hence available) than CA to react and slow down the AAPH-mediated oxidation of fluorescein. It can be noticed that the ORAC system is not a partitioned one, therefore the two main influent parameters which must be considered are the reactivity and the solubility of the active molecule. The reactivity can be directly linked to the number of catechol, as well as its electron delocalization area, its phenolic ring freedom of rotation, and its steric hindrance. Mesomeric effects of electron-withdrawing groups such as carboxylic acid in RA (but not in CA) should also be taken into account.

Regarding ORAC assay, a plateau appeared between 0-40 % ethanol which corresponds to the optimal range of solvent to recover extracts with high ORAC values. The

TE/g extract) % EtOH (v/v) (a) (b)

IV.3.3.3 DPPH scavenging activity

Focusing our attention on RA and CA, the former appears as 2.4 times better than CA as DPPH scavenger (Figure IV-6 (a), insert): IC50 of RA is 113 µM (0.041 g/L), while that of CA is 270 µM (0.090 g/L). Surprisingly, this is in contradiction with several reports in literature. For example, Erkan et al. found that CA was 2.2 times better than RA as DPPH free radical scavenger [START_REF] Erkan | Antioxidant activities of rosemary (Rosmarinus Officinalis L.) extract, blackseed (Nigella sativa L.) essential oil, carnosic acid, rosmarinic acid and sesamol[END_REF]. Others, such as Luis et al. showed that RA and CA have similar activity [START_REF] Luis | Seasonal variations of rosmarinic and carnosic acids in rosemary extracts. Analysis of their in vitro antiradical activity[END_REF][START_REF] Luis | UV-B radiation effects on foliar concentrations of rosmarinic and carnosic acids in rosemary plants[END_REF]. If the reason for such discrepancies is not yet clear for us, it is worth noting that our results can be well explained from a molecular standpoint. Indeed, as previously mentioned, RA encompasses two catechol groups, while CA has only one. The presence of a catechol is a key factor for antioxidant activity, in agreement with the low bond dissociation energy (homolytic breakdown) of the corresponding OH groups [START_REF] Rice-Evans | Structure-antioxidant activity relationships of flavonoids and phenolic acids, Free Radic[END_REF][START_REF] Goupy | Quantitative Kinetic Analysis of Hydrogen Transfer Reactions from Dietary Polyphenols to the DPPH Radical[END_REF] which is due to the phenoxy radical (AO • ) stabilization through the formation of an intramolecular hydrogen bond between the two phenolic hydroxyls in ortho position. In contrast, meta or para-dihydroxy substitutions would not favour the establishment of such a bond. Apart from the number of catechols, RA has another structural trait that makes it a better reducer than CA in polar and noncompartmentalized system such as DPPH in methanol, that is its larger electron delocalization area (throughout the caffeoyl moiety of RA). Mention should also be made that the phenolic hydroxyls of CA are sterically hindered by the vicinal isopropyl and the carboxylic acid as well. Finally, unlike for RA, the phenolic ring of CA cannot rotate freely with regard to the remaining part of the molecule, which should theoretically hinder the contact between DPPH and CA. Noteworthy, both molecules are readily soluble in methanol, so, the DPPH method does not seem to discriminate them on the basis of their solubility and mass transfer. Ethanol ranging from 10-30 % must be selected to maximize TPC, DPPH and ORAC values. This range of solvent differs from the optimal ratios found for RA and CA's solubility (100 % ethanol) and for the global extraction yields (50-80 % ethanol). It is obvious, here, that the results are influenced by the nature of the tests carried out: all of them take place in polar systems (aqueous or methanol) where polar compounds like RA are favored over less polar molecules like CA to react since they are more soluble, hence more available for oxidants. oil-in-water emulsion that RA exerted a strong synergistic effect when combined to αtocopherol. [START_REF] Panya | Interactions between α-Tocopherol and Rosmarinic Acid and Its Alkyl Esters in Emulsions: Synergistic, Additive, or Antagonistic Effect?[END_REF] Interestingly, alkyl esters of RA produced additive and/or antagonistic effects with α-tocopherol in the same system, suggesting that the compartmentation of RA in the aqueous phase and that of α-tocopherol in the oily phase was required for a synergy to occur. In the present study, the TPC was evaluated in a non-compartmentalized system, which could explain why no synergy was observed between a water-soluble antioxidant such as RA and an oil-soluble antioxidant such as CA. Regardless of the mechanism of action, it is thus likely that in our case, reducers other than RA and CA-like compound impacts most of the overall reducing capacity of the extracts toward Folin-Ciocalteu reagent. Therefore, natural extracts of rosemary leaves exhibit much higher reducing activity than the one theoretically inferred from the individual effect of pure standards of CA and RA demonstrating the interest to use plant extracts with complex composition instead of simple mix of synthetic antioxidants.

As shown in

In previous part, we concluded that CA was better extracted with high amount of ethanol in extraction solvent whereas RA was more efficiently extracted with lower amount (30 % ethanol). Based on this result, we designed a bio-refinery process and proposed to extract consecutively RA and CA from rosemary in one single process. As described in section II.4. IV. In a second part, based on previous results, a bio-refinery concept was developed to extract both RA and CA in a single process. The challenge was achieved since 82.0 % of available CA and 71 % of available RA were recovered separately in two independent extracts from the same raw material. As perspective, it could be envisaged to valorize spent rosemary leaves after the three first extractions for their content in fibers or proteins (provided they are not degraded). Chemat, Towards a "dry" bio-refinery without solvents or added water using microwaves and ultrasound for total valorization of fruit and vegetable by-products, Green Chem. 18 (2016) 3106-3115. doi:10.1039/C5GC02542G.

CONTEXT

Huge amounts of fruits and vegetables press cakes are daily generated by juice processing industry. They are generally considered as waste and their elimination is often complicated, polluting and expensive, particularly when large volumes are implicated. In this context, there are obvious economic and environmental interests to valorize this biomass into valuable products.

ABSTRACT

This study aims at total valorization of fruits and vegetables by-products moving towards developing an original concept of "dry" bio-refinery (DBR). Indeed, all valuable products were recovered from food by-products without addition of solvents or water and using green processes. Ginger was chosen as reference matrix since its juice processing generates a large amount of press cake currently considered as waste. Therefore, in this study, after juice processing, ginger press cake (GP) was firstly treated by microwave hydrodiffusion and gravity (MHG) process to recover essential oil (EO) and constituent water present in ginger by-products. Gingerols and 6-shogaol remaining into the ginger presscake residue after MHG (GPMHG) were then extracted by ultrasound assisted extraction (UAE) at different ultrasonic intensities (UI) using constituent water as solvent. The assessment of microwave (MW) power enabled to determine that a power of 1.6 W/g was optimal to recover constituent water and EO, preserving extract quality in a reduced time. The mass extraction yield was enhanced by UAE (16.7 W/cm 2 ; 0.303 W/cm 3 ) with an increase of 126 % compared to conventional maceration (CM). Total valorization of ginger by-products was achieved since juice, EO, extract rich in phenolics, and solid residue rich in fibers and phenolic acids were obtained from ginger rhizomes (GR) using DBR without solvent and added water. Finally, the performances of DBR and conventional bio-refinery (CBR) were compared in term of process time, energy consumption, quantity of waste and quantity of solvent.

V.1 INTRODUCTION

In 2012, the world vegetable and fruit production was 1,106,133,866 and 636,544,883 tons respectively (FAOSTAT-FAO statistical database 2015). Most of this production is destined to food processing industry which generates, after processing, a huge amount of by-products often considered as wastes, since they still constitute a resource for high-value compounds [START_REF] Pfaltzgraff | Food waste biomass: a resource for high-value chemicals[END_REF]. These high-value compounds provide a large field of application since they can be used for instance as antioxidants, natural chelating agents, or even as bio-solvents or bio-fuels after special treatment [START_REF] Pfaltzgraff | Food waste biomass: a resource for high-value chemicals[END_REF]243]. Therefore, the production of added products from industrial by-products is considered as a challenge for the current natural product industry and more generally for the extraction field.

Only a few studies have been investigating valorization of by-products. For example, using grape seeds issued from the wine-making industry to recover oil [START_REF] Passos | Enhancement of grape seed oil extraction using a cell wall degrading enzyme cocktail[END_REF] and phenolic compounds [START_REF] Boussetta | Application of electrical treatments in alcoholic solvent for polyphenols extraction from grape seeds[END_REF], orange peels from the orange juice industry for pectin and flavoring products [START_REF] Casas-Orozco | Process development and simulation of pectin extraction from orange peels[END_REF][START_REF] Bocco | Antioxidant Activity and Phenolic Composition of Citrus Peel and Seed Extracts[END_REF]. More recently, the concept of bio-refinery of a plant is increasingly investigated for maximal valorization of natural products from a raw material [START_REF] Kamm | Biorefineries -Multi Product Processes[END_REF][START_REF] Pfaltzgraff | Food waste biomass: a resource for high-value chemicals[END_REF][START_REF] Uçkun Kıran | Platform chemical production from food wastes using a biorefinery concept[END_REF].

Bio-refinery of natural products intends to value all bioactive compounds from a raw material, which implies to extract those bioactives using different extraction processes. However, an industrial application of bio-refinery would imply extensive use of solvents, high energy costs and extensive extraction duration. In this scope, the use of green extraction is an alternative for well-reasoned processing [START_REF] Chemat | Green Extraction of Natural Products: Concept and Principles[END_REF].

In the general frame of green chemistry, green extraction processes focus on process intensification. The objective of these green extraction processes is to achieve faster extraction rate and more effective energy use, increased mass and heat transfer, reduced equipment size, and reduction of processing steps. For this, innovative technologies can be used such as microwaves (MW) [START_REF] Thirugnanasambandham | Microwave assisted extraction process of betalain from dragon fruit and its antioxidant activities[END_REF][START_REF] Prakash Maran | Microwave assisted extraction of pectin from waste Citrullus lanatus fruit rinds[END_REF], ultrasound (US) [START_REF] Chen | Optimisation of ultrasonic-assisted extraction of phenolic compounds, antioxidants, and anthocyanins from sugar beet molasses[END_REF][START_REF] Maran | Optimization of ultrasound-assisted extraction of natural pigments from Bougainvillea glabra flowers[END_REF], supercritical fluids [START_REF] Herrero | Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review[END_REF][START_REF] Sabio | Lycopene and β-Carotene Extraction from Tomato Processing Waste Using Supercritical CO2[END_REF], electro-technologies [START_REF] Boussetta | Extraction of valuable biocompounds assisted by high voltage electrical discharges: A review[END_REF][START_REF] Segovia | Improvements in the aqueous extraction of polyphenols from borage (Borago officinalis L.) leaves by pulsed electric fields: Pulsed electric fields (PEF) applications[END_REF] or instantaneous controlled decompression DIC [START_REF] Chemat | Solvent-free extraction of food and natural products[END_REF][START_REF] Berka-Zougali | Extraction of essential oils from Algerian myrtle leaves using instant controlled pressure drop technology[END_REF]. Those green extraction processes have proved their efficiency for extraction of natural products [START_REF] Shirsath | Intensification of extraction of natural products using ultrasonic irradiations-A review of current status[END_REF][START_REF] Rombaut | Green extraction processes of natural products as tools for biorefinery[END_REF] but more rarely in the case of a bio-refinery [START_REF] Boukroufa | Biorefinery of orange peels waste: A new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil, polyphenols and pectin[END_REF]. A major interest would be to achieve a bio-refinery without the use of extraction solvents.

The reference matrix chosen for this study is ginger (2.1 million tons in 2012, FAOSTAT-FAO statistical database 2015), due to its composition in valuable natural compounds. It contains products of interest such as essential oil (EO) (1 -4 %), phenolics (gingerols and 6-shogaol, 1 -2 %), and total carbohydrates (60 -75 %) [START_REF] Prakash | Chemical composition and antioxidant properties of ginger root (Zingiber officinale)[END_REF][START_REF] Konar | Value-added bioethanol from spent ginger obtained after oleoresin extraction[END_REF]. Ginger, and more specifically rhizomes are variously used as food product or traditional medicine [START_REF] Eric Chan | Antioxidant properties of ginger leaves: An overview[END_REF]. In food industry, rhizomes are mainly used as spice or condiment (fresh or dried), candy or as juice after cold mechanical pressing. Due to the fact that mechanical pressing does not alter the chemical composition of the pressed product, this process provides huge amounts of press cakes still containing high amounts of bioactive compounds, but currently considered as waste.

Our study aims at total valorization of ginger rhizome press cake generated after juice production moving towards developing an original concept of "dry" bio-refinery (DBR). The novelty of this work relies on extraction of compounds achieved without addition of solvent or water. The only water used in the process was the constituent water extracted from ginger itself. To recover these different fractions, bio-refinery was applied using green extraction processes (MHG followed by UAE) and quality of the corresponding extracts was determined. Ultimately, the performances of bio-refinery using green extraction and conventional extraction were compared.

V. Analysis of the different EO and GPMHG recovered after MHG were performed to assess a potential change in their composition according to MW power. (EO drops remained on reactor walls). To prevent this loss of yield, we could imagine the use of a double layer extractor to limit the phenomenon of condensation on glassware walls.

V.3.1.2 Evaluation of essential oil quality

Considering composition, zingiberene is generally considered as a characteristic compound in ginger EO. In literature, it is mainly found between 20 % and 30 % in EO [START_REF] Cornell | Composition and distinctive volatile flavour characteristics of the essential oil from Australian-grown ginger (Zingiber officinale)[END_REF][START_REF] Van Beek | Isolation and identification of the five major sesquiterpene hydrocarbons of ginger[END_REF]. GC-FID analysis of EO obtained by HD was in accordance with literature as zingiberene content was 25.2 %. In EO obtained by MHG, zingiberene percentage was constant for powers from 0.8 W/g to 1.6 W/g (medium powers) with a content of 23 to 25 %.

However, for extreme powers (0.6 W/g and 1.8 W/g), zingiberene content decreased significantly (both 18.4 %).

The differences of aromatic profiles between EO obtained by the reference process and MHG indicate that the extraction process impacts EO quality. This result has already been shown and explained in previous works. For example, it is reported that the contact between a plant material and the solvent during the process can lead to EO degradation [START_REF] Filly | Solvent-free microwave extraction of essential oil from aromatic herbs: From laboratory to pilot and industrial scale[END_REF] did not cause the degradation of gingerols and 6-shogaol when comparing results obtained for GP and GPMHG. They were even better extracted when MHG treatment was performed (0.90 g/100 g of GP and from 1.06 to 1.37 g/100 g of GPMHG). As described by Zill-e-Huma et al. [START_REF] Zill-E-Huma | A novel idea in food extraction field: Study of vacuum microwave hydrodiffusion technique for by-products extraction[END_REF][START_REF] Zill-E-Huma | A remarkable influence of microwave extraction: Enhancement of antioxidant activity of extracted onion varieties[END_REF], MW seem to alter cell walls of ginger, so gingerols and 6-shogaol were more available in GPMHG than in GR and GP for extraction. It can be underlined that 6-shogaol content in GPMHG was higher than in GP (0.08-0.11 % against 0.02 % respectively), certainly due to high temperature associated to MHG process. However these amounts of 6shogaol were insignificant compared to contents in gingerols recovered (for GPMHG at 1.6 W/g: 0.08 % of 6-shogaol and 1.37 % of gingerols in plant material). Extraction at power beyond 1 W/g did not involve the degradation of phenolic compounds in GPMHG as described for onion polyphenols in previous work [START_REF] Zill-E-Huma | A novel idea in food extraction field: Study of vacuum microwave hydrodiffusion technique for by-products extraction[END_REF].

The previous results enabled to select a MHG power of 1.6 W/g as optimal for the second step of our DBR (Figure II-6) since this power enabled to recover total removable water and EO in 20 min, preserving EO quality and without degradation of phenolics in GPMHG. Therefore the recovery of these preserved phenolics from GPMHG will constitute the third step of the "dry" bio-refinery developed in the study. Phenolic compounds are conventionally extracted from ginger with 75 % ethanol [START_REF] Mukherjee | An approach towards optimization of the extraction of polyphenolic antioxidants from ginger (Zingiber officinale)[END_REF]. However, industrials are looking for green processes to extract bioactives from plants without addition of organic solvent. In this work, an alternative process has been investigated

to extract phenolics from GPMHG by using only water as solvent and more specifically constituent water previously recovered from GP by MHG (Figure II-6). Solubilities of 6gingerol, 8-gingerol, 10-gingerol and 6-shogaol were predicted with ACD-Lab software as 0.26 g/L, 0.038 g/L, 0.91 mg/L and 0.0046 g/L respectively, which shows that water could be used as an alternative solvent to solubilize these compounds during UAE. We are aware that is it is not the solvent of choice according to gingerols and 6-shogaol solubility, but it fits perfectly with the concept of bio-refinery developed in the study. Moreover, solubilization performance towards the compounds of interest could be improved since it is not simple water but constituent water of ginger.

UAE is a process which is used to increase extraction yield of various phytochemicals [START_REF] Shirsath | Intensification of extraction of natural products using ultrasonic irradiations-A review of current status[END_REF][START_REF] Vilkhu | Applications and opportunities for ultrasound assisted extraction in the food industry -A review[END_REF]. US emitted by probe or in bath generate microbubbles which alter vegetal cells by cavitation phenomenon enhancing extraction of targeted compounds [START_REF] Chemat | Applications of ultrasound in food technology: Processing, preservation and extraction[END_REF]. US were applied to GPMHG in water at different UI (with the corresponding PD): 4.4 W/cm 2 (0.080 W/cm 3 ), 9.4 W/cm 2 (0.170 W/cm 3 ), 13.4 W/cm 2 (0.242 W/cm 3 ) and 16.7 W/cm 2 (0.303 W/cm 3 ). A CM was performed as reference. A monitoring of dry matter content in the liquid phase was carried out to compare the kinetics of solubilization of dry matter according to the UI. Results obtained are presented in Figure V-4.

Until 25 min of extraction, dry matter evolution followed the same trend for each UI assessed. Beyond 25 min of UAE, no difference was noticed between CM, UAE (4.4 W/cm 2 ; 0.080 W/cm 3 ) and UAE (9.4 W/cm 2 ; 0.170 W/cm 3 ) as they all reached 0.20 to 0.24 % of dry mass content in extract after 90 min. A significant increase was observed for UAE (13.4 W/cm 2 ; 0.242 W/cm 3 ) after 90 mins with a dry mass content of 0.35 %. The higher yield was reached with UAE (16.7 W/cm 2 ; 0.303 W/cm 3 ) since an extract with a dry mass content of 0.48 % was recovered at the end of experiment. At the end of each experiment, liquid extract was separated from the solid residue by filtration on filter paper and concentrated by water removal. Mass extraction yields were calculated from final dry masses and reported on Figure V-5. US with a high UI (13.4 W/cm 2 ; 0.242 W/cm 3 and 16.7 W/cm 2 ; 0.303 W/cm 3 ) had a positive impact on the mass extraction yield with an increase of 126 % from CM to UAE (16.7 W/cm 2 ; 0.303 W/cm 3 ). This increase in mass extraction yield could be due to a solubilization of some natural polymers which have been partially disintegrated by US and solubilized into water. Indeed, ultrasonic processes have been reported to impact cell wall polymers such as cellulose, hemicellulose and pectin and non-structural polymers such as starch [START_REF] Jambrak | Ultrasound effect on physical properties of corn starch[END_REF][START_REF] Ebringerová | The effect of ultrasound on the structure and properties of the water-soluble corn hull heteroxylan[END_REF][START_REF] Zhang | Ultrasound effects on the degradation kinetics, structure and rheological properties of apple pectin[END_REF][START_REF] Wong | Molecular weight and crystallinity alteration of cellulose via prolonged ultrasound fragmentation[END_REF]. The degradation results in a modification of macromolecular structures and a decrease of molecular weight which leads to an improvement of the solubilization of polymers. However, US effect has to be assessed on more complex structures since it is not obvious that these simplified models described for US effect on single polymers would be valid for plant materials, which are composed of a large network of various polymers. On Figure V-5, quantities of phenolics extracted from plant material are also reported.

We were aware that gingerols solubility into pure water at ambient temperature is quite limited, but we wanted US to intensify as far as possible their extraction in this solvent. It can be noticed that phenolics content in extract did not increase as much as the global dry mass: quantity of phenolics extracted was improved by 29 %, by comparing CM to UAE (16.7 W/cm 2 ; 0.303 W/cm 3 ). Quantity of gingerols and 6-shogaol available in GPMHG is reported in as the process of choice to extract gingerols and 6-shogaols into water, since 74 % of available phenolic compounds remained in the solid residue. [ [START_REF] Chemat | Green Extraction of Natural Products: Concept and Principles[END_REF]. Indeed, extraction methods are designed considering these aspects which aim at recovering a natural and safe extract (principle 6) reducing as much as possible the use of organic solvents (principle 2), the energy consumption (principle 3) and the process time (principle 5). Well-reasoned sourcing (principle 1) and production of by-products with a high added value instead of waste (principle 4) have to be assessed as well. Literature reports that industrials have already developed some tools based on these principles to assess the sustainability of their processes in a context of continuous improvement [START_REF] Leseurre | Eco-footprint: a new tool for the "Made in Chimex" considered approach[END_REF]. In this study, a simplified view of the bio-refineries was assessed. The six parameters considered were defined and calculated as follows: 74 % for antioxidants) compared to a CBR, the objective of the study is achieved since a total valorization of ginger by-products into high valued products was performed without addition of any solvent. Indeed, from GR were obtained a juice, an EO, an extract rich in phenolics, and a solid residue rich in fibers and phenolic acids, which can be thereafter incorporated in food formulations.

 Raw material ( Principle

List of figures

  Karl pour sa disponibilité et ses conseils avisés, Lise pour ses tuyaux « bien vivre sa thèse », Pauline (alias Popo) pour son professionnalisme, sa minutie et nos fous rires (I love Reyssouze) et Ludo pour sa pédagogie, ses trucs et astuces de labo et son côté clown (attend je suis en rush là…). Merci aussi aux filles de la cosméto Caro et Jessy avec qui j'ai partagé de si bons moments et fous rires, ainsi qu'à Alexis et à Gaétan ; merci à toute l'équipe Nutra : Leila F., Thi, Yoann, Mélissa, Lucile B. et Laure, avec mention spéciale pour Mélissouille et II.5.6 High performance thin layer chromatography (HPTLC) coupled to DPPH free radical scavenging activity measurement ........................................................... II.5.7 LC-MS identification ......................................................................................... II.6 CALCULATIONS ..................................................................................................... CHAPTER III . PROCESS INTENSIFICATION....................................... III.1 INTRODUCTION ................................................................................................... III.2 MATERIALS AND METHODS ............................................................................ III.3 RESULTS AND DISCUSSION .............................................................................. III.3.1 Comparison of extraction processes in terms of mass extraction yields ..... III.3.2 Processing impact towards the extraction efficiency of rosmarinic, carnosic and ursolic acids ........................................................................................................... III.3.3 Investigation on the conversion of CA into carnosol ..................................... III.3.4 Energy consumption ......................................................................................... III.4 CONCLUSION ........................................................................................................ CHAPTER IV . SUBSTITUTION OF SOLVENT ...................................... IV.1 INTRODUCTION ................................................................................................... IV.2 MATERIALS AND METHODS ............................................................................ IV.3 RESULTS AND DISCUSSION .............................................................................. IV.3.1 Solubility of targeted compounds in ethanol:water mixtures ....................... IV.3.1.1 Theoretical solubilities: COSMO-RS simulations ....................................... IV.3.1.2 Experimental solubilities .............................................................................. IV.3.2 Extraction of targeted compounds in ethanol:water mixtures ..................... IV.3.2.1 Extraction yield and recovery rate ............................................................... IV.3.2.2 Is plant extraction all about solute solubility in the solvent? ....................... IV.3.3 Antioxidant activity of rosemary extracts obtained using various ethanol:water mixtures ................................................................................................ IV.3.3.1 Determination of the total phenolic content (TPC) through the reducing activity ........................................................................................................................ IV.3.3.2 Hydrophilic ORAC assay............................................................................. IV.3.3.3 DPPH scavenging activity ........................................................................... IV.3.4 Contribution of RA and CA to extract activity .............................................. IV.3.5 Towards a bio-refinery of rosemary ............................................................... IV.3.5.1 Development of bio-refinery process ........................................................... IV.3.5.1.1 Preliminary assay .................................................................................. IV.3.5.1.2 Impact of extraction time and temperature ........................................... IV.3.5.2 Comparison with existing process ............................................................... IV.4 CONCLUSION ........................................................................................................ CHAPTER V . VALORIZATION OF BY-PRODUCTS ............................ V.1 INTRODUCTION ..................................................................................................... V.2 MATERIALS AND METHODS .............................................................................. V.3 RESULTS AND DISCUSSION ................................................................................ V.3.1 Dry extraction of essential oil from ginger press cake by MHG .................... V.3.1.1 Impact of microwave power on MHG extraction efficiency of essential oil and constituent water ........................................................................................................ V.3.1.2 Evaluation of essential oil quality ................................................................. V.3.1.3 Impact of microwave pretreatment on phenolics extraction efficiency ........ V.3.2 Ultrasound assisted extraction of gingerols and 6-shogaol from GPMHG ... V.3.3 Large scale microwave and ultrasound assisted extraction ........................... V.3.4 Process assessment according to the six principles of green extraction ........

  thèse. Les protocoles et techniques d'extraction, ainsi que les méthodes d'analyse qualitative et quantitative seront présentés. Le chapitre III proposera d'intensifier le procédé d'extraction des acides rosmarinique, carnosique et ursolique à partir du romarin par l'utilisation d'ultrasons et de micro-ondes. Trois équipements ultrasons et trois équipements micro-ondes seront étudiés. Les technologies alternatives utilisées seront comparées aux procédés conventionnels. L'efficacité et la sélectivité d'extraction, ainsi que la consommation énergétique, seront évaluées en fonction du procédé utilisé (Figure 1).

Figure 1 .Figure 2 .

 12 Figure 1. Schéma expérimental suivi dans le chapitre III.

Figure 3 .

 3 Figure 3. Schéma expérimental suivi dans le chapitre V.

Figure I- 1 .

 1 Figure I-1. Types of compounds extracted from plant materials.

Figure I- 2 .

 2 Figure I-2. Principle of intensification.

Figure I- 3 .

 3 Figure I-3. Essential inputs and outputs on an extraction process related to the six principles of green extraction.

Figure I- 4 .

 4 During the 1970's, no less than 30 tons of bark were collected for clinical trials, considering that 10 kg of dry bark produce only 1 g of taxol after extraction and purification. These low yields may result in an overexploitation of trees; however, due to the complexity of the molecule of interest, a synthetic way is not economically viable. In this context, a large number of research projects have been aimed at finding alternatives to felling trees of this threatened species. Since 1980, paclitaxel and docetaxol (Taxotere®) are prepared by semi-synthesis from the natural precursor, 10-deacetylbaccatine III, extracted from needles and branches (renewable resource) of different yew tree species.

Figure I- 4 .

 4 Figure I-4. Paclitaxel.

Figure I- 5 .

 5 Figure I-5. (-)-α-bisabolol.

Figure I- 6

 6 Figure I-6. Artemisinin.

  clary sage (Figure I-7).

Figure I- 7

 7 Figure I-7. Sclareol.

Figure I- 8 .

 8 Figure I-8. Plant milking technology. (PAT plant milking©).

Figure I- 9 .

 9 Figure I-9. Scheme of microwave assisted hydrodistillation processing.

Figure I- 10 .

 10 Figure I-10. MHG extraction processing.

  results in the rupture of the hydrogen bonding network and causes an important decrease of the dielectric constant. As illustrated in Figure I-12, it is possible to reach near-zero values, corresponding to very less polar solvents. When water temperature exceeds 100 °C under pressure, we talk about subcritical water.

Figure I- 12 .

 12 Figure I-12. Evolution of water dielectric constant regarding temperature and comparison with conventional solvents (from [43]).

Figure I- 13 .Figure I- 14 .

 1314 Figure I-13. Surfactant/hydrotrope structure.

Figure I- 15

 15 Figure I-15 illustrates the difference in behavior of surfactants and hydrotropes in aqueous solution.

Figure I- 15 .

 15 Figure I-15. Surfactant and hydrotrope behavior according to their concentration in aqueous solution.

Figure I- 16 .

 16 Figure I-16. Determination of solubility sphere using Hansen Solubility Parameters.

  3.3.2 COSMO-RS calculations[START_REF] Sicaire | Solvants alternatifs et techniques innovantes pour l'éco-extraction des huiles végétales à partir de graines oléagineuses[END_REF][START_REF] Filly | Solvants alternatifs pour l'extraction des composés odorants : Modélisation et Expérimentation[END_REF]

Figure I- 17 .

 17 Figure I-17. Step calculation with COSMO-RS: (a) molecule emerged; (b) molecular surface; (c) energies of local surface interactions between σ-profiles of targeted molecules and two solvents (water, ethanol); (d) σ-potentials of targeted molecules and solvent.

Figure I- 19 .

 19 Figure I-19. Process optimization procedure (adapted from[START_REF]Extraction optimization in food engineering[END_REF]).

  Figure I-21, US can be classified in two main categories [166,167]:  Power US (20 kHz -1 MHz, high-intensity sonication I > 1 W/cm 2 ) employed for extraction and processing applications  Diagnostic US (1 MHz -10 MHz, low-intensity sonication I < 1 W/cm 2 ) typically used as a non-destructive analytical technique (quality assurance, process control…), providing more particularly physico-chemical properties of matter.

Figure I- 21 .

 21 Figure I-21. Ultrasound frequency range.

  Power US are the most used in extraction field. They are two such categories (Figure I-21): low frequency US (16 -100 kHz) for which physical effects (agitation, vibration, cleaning, degassing, emulsification) dominate and high frequency US (100 kHz -1 MHz) for which chemical effects (reactional mechanism change, generation of free radicals…) are more important [167]. Extraction effects of sonication are mainly driven by the force of acoustic cavitation. Indeed, the propagation of US through a medium induces cycles of compressions and rarefactions in the molecules of the medium (Figure I-22). Such series of compressionsrarefactions induce an acoustic pressure Pa in the medium defined by Eq. I-8 and Eq. I-9 [61]. Eq. I-8. Pa = PA sin2π f t Eq. I-9 PA = (2 I ρ c) 1/2

Figure I- 22 .

 22 Figure I-22. Compression and rarefaction cycles induced by an ultrasound wave (from [61]).

  the effects of solvent type, extraction temperature and the presence of dissolved gases on ultrasonic cavitation and on extraction efficiency[START_REF] Sicaire | Solvants alternatifs et techniques innovantes pour l'éco-extraction des huiles végétales à partir de graines oléagineuses[END_REF][START_REF] Tiwari | Ultrasound: A clean, green extraction technology[END_REF].

Figure I- 23 .

 23 Figure I-23. Collapse of cavitation bubble and release of targeted compounds from plant material. (a) Bubble close to plant surface, (b) Collapse during compression phase, (c) Microjet toward cells, (d)Release of cell content (from[START_REF] Sicaire | Solvants alternatifs et techniques innovantes pour l'éco-extraction des huiles végétales à partir de graines oléagineuses[END_REF]).

I. 4 . 3 . 3 . 2

 4332 Principle of MWMW are electromagnetic waves with a frequency range comprised between 300 MHz and 300 GHz (corresponding to wavelengths ranging from 1 mm to 1 m). On the electromagnetic spectrum illustrated in Figure I-24, they are located between radio and infrared waves. The most common frequency used in domestic oven or in laboratory and industrial equipment is 2450 MHz, generally with a power comprised between 100 W and 1000 W[START_REF] Chemat | Chapitre 5: Extraction assistée par micro-ondes[END_REF].

Figure I- 24 .

 24 Figure I-24. Electromagnetic spectrum (from [170]).

Figure I- 25 .

 25 Figure I-25. Illustration of the electromagnetic wave.

Figure I- 26 .

 26 Figure I-26. Comparison between MW heating (a) and conventional heating (b).

Figure I- 27 .

 27 Figure I-27. Microwave oven components.

I. 4 . 3 . 4

 434 is directed by the waveguide. It enables precise control of electric field but it is reserved for the treatment of small volume experiments.In a multimode cavity, electromagnetic waves are reflected from the walls and scattered randomly. This type of cavity allows to perform experiments with larger amounts of product, but the control of field distribution is quite difficult and high temperature gradients can be observed in the product. Wave brewers or rotating plates can be used to overcome this problem. Innovative processes Contrary to previous section where innovative technologies were only used to assist conventional solid-liquid extraction, in this part "innovative processes" refer to completely different processes than conventional ones, which request specific facilities or solvents.When optimization of existing process or addition of external technologies during the process are not viable energetically, it is sometimes necessary to reconsider completely global procedure. Innovative process may be adopted for pre-treatment phase upstream from extraction process, or may be the process itself. The main innovative technologies which can be used in current extraction field at industrial level are summarized in Figure I-28.

Figure I- 28 .

 28 Figure I-28. Assessment of available innovative processes for green extraction.

[ 93 ]

 93 . In another case, deodorization by instant controlled pressure drop (DIC) was performed on rosemary leaves before ethanolic extraction. It permitted to improve significantly rosmarinic acid (RA) extraction yield since that of DIC-treated leaves was twice as much as untreated leaves. Moreover, DIC-treatment step enabled to recover EO and consequently deodorize plant material. EO extraction was also intensified as DIC-treatment lasted 3 min against minimum 4 h for conventional HD [94]. As last example of successful plant material pre-treatment with innovative process, Kubra et al. compared different drying method to dehydrate ginger. MW drying resulted in reduced drying time and maximal volatiles retain in specific conditions [95]. Innovative technologies also offers efficiency opportunities as main extraction process. Pressurized liquid extraction (PLE) appears particularly as an efficient and sustainable approach in various studies. Indeed, Hu et al. used this process to extract phenolics from ginger with ethanol or water as solvent [96]. It resulted in reduced extraction time and solvent consumption, and consequently in a decrease of energy consumption and costs. Extraction solvent 70 % ethanol, pressure 1500 psi, temperature 100 °C and extraction time 20 min were determined as the optimal conditions to maximize extraction efficiency. Under these conditions, actives recovery was 106.8 %, 109.3 % and 108.0 % for 6-gingerol, 8-gingerol and 10-gingerol respectively, compared to corresponding Soxhlet extraction. PLE was also performed to extract antioxidant from rosemary leaves with ethanol [97]. Good results were obtained in terms of extraction yields, extract activity, and both polarities antioxidants extraction (RA and carnosic acid (CA)). I.5 PRINCIPLE 4: PRODUCTION OF CO-PRODUCTS INSTEAD OF WASTE TO INCLUDE THE BIO-AND AGRO-REFINING INDUSTRY. I.5.1 Context Industrial extraction of natural products mainly includes the juice production from fresh fruits and vegetables, the production of vegetable oil from various seeds and the active compounds extraction from diverse biomasses using liquid solvents. It often focuses on the extraction of one single product of interest from an initial biomass and consequently generates, each year, huge amounts of waste and by-products (about 220 million tons).

  added value (Figure I-29) [98].

Figure I- 29 .•

 29 Figure I-29. Relative classification of food waste and by-products management options.

  Figure I-30 relates some examples of bio-based product applications in current lines of business.

Figure I- 30 .

 30 Figure I-30. Potential products and bio-products from biological biomass (adapted from[START_REF] Kamm | Biorefineries -Multi Product Processes[END_REF]).

•

  Activated carbon • Oxy fuel additives • Phenols and furfural • Specialty chemicals • Fatty and acetic acids • Industrial surfactants • Agricultural chemicals • Oils and inks • Dyes and pigments • Paints and vernishes • Detergents and cleaners • Industrial adhesives • Biopolymers and films • Composite materials • Solid: coke, lignin, bagasse • Liquid: ethanol, methanol, fuel oil • Gaseous: syngas, methane, hydrogen I.5.2 Good practices guidelines Good practices guidelines regarding the management of extraction waste and byproducts have two main objectives [15]: The development of valorization pathways for a better use of raw material and complete exploitation of by-products o Performing a second extraction/process to generate other high value products o Using residual raw material to feed livestock o Converting the residual biomass into energy  The reduction of effluents and waste in terms of quantity and harmfulness with: o The well-reasoned conception of processes to anticipate and reduce waste production o The limitation of liquid and gaseous effluents, particularly greenhouse gases o The choice of low environmental impact recycling processes. I.5.3 Success stories This section aims at presenting some achievements in terms of food and extraction byproducts valorization. These examples illustrate previous good practices guidelines regarding principle 4. Animal feed application, high value compounds recovery and conception of biorefinery are more particularly developed. I.5.3.1 Animal feed Currently, food and extraction by-products are hugely used for livestock feed because

Figure I- 31 .

 31 Figure I-31. Flowsheet regarding the valorization of fruits and vegetables by-products (from [112]).

  directly patterned on the petroleum refinery system (Figure I-33).

Figure I- 33 .

 33 Figure I-33. Simplified diagram of petroleum refinery system.

  oil (C 20 to C 70 ) Lubricating oil (C 20 to C 50 ) Diesel oils (C 14 to C 20 ) Kerosine (C 10 to C 16 ) Petrol (C 5 to C 10 ) Naphtha (C 5 to C 9 ) Gases (C 1 to C 4 ) Heated crude oil FRACTIONATING COLUMNbio-refinery. Plus, the increase in agricultural raw material demand might result in intensive culture, intensive use of fertilizers and pesticides to improve production yields[START_REF] Cherubini | The biorefinery concept: Using biomass instead of oil for producing energy and chemicals[END_REF][START_REF] Laurent | Le bioraffinage, une alternative prometteuse à la pétrochimie[END_REF][START_REF] Clark | Green chemistry for the second generation biorefinery-sustainable chemical manufacturing based on biomass[END_REF].

Figure I- 34 .

 34 Figure I-34. Simplified diagram of first and second generation bio-refineries.

  Figure I-35. Towards a bio-refinery of orange peels (adapted from[START_REF] Boukroufa | Biorefinery of orange peels waste: A new concept based on integrated green and solvent free extraction processes using ultrasound and microwave techniques to obtain essential oil, polyphenols and pectin[END_REF]).

Figure I- 36 .Figure I- 37 .

 3637 Figure I-36. Simplified pressure/temperature phase diagram for carbon dioxide.

Figure I- 38 .

 38 Figure I-38. Ankom XT15 extractor.

  characteristics (Figure I-40):  Naturalness;  High quality with active and non-denatured compounds;  High functionality (antioxidant, antimicrobial, flavoring, coloring properties…);  Complete safety; Accordance with specific legislations regarding the application sector (food processing, cosmetics, pharmaceutical industry…);  Low environmental footprint (determination with the LCA approach).

Figure I- 40 .

 40 Figure I-40. Characteristics defining an "eco-extract".

Figure I- 41 .

 41 Figure I-41. Examples of labels with naturalness values.

Figure I- 42 .

 42 It includes the extraction of raw materials, the processing, the distribution and transport, the utilization and finally the end-of-life treatment.

Figure I- 42 .

 42 Figure I-42. Whole life cycle of a product.

Figure I- 43 .

 43 Figure I-43. Life Cycle Assessment methodology requirements.

  business or BEE V3.1 for packaging. Open LCA and SimaPro are examples of more universal software which can be used in extraction field. Databases such as Ecoinvent 2.1, Agribalyse, Definition of the functional unit Life Cycle Inventory (LCI)  Inputs: energy resources (fuel, electricity…) and nonenergy resources (solvent, water, packaging…) Outputs: emissions in the air, soil and water

Figure I- 44 .

 44 Figure I-44. "Gate to gate" approach in Life Cycle Assessment methodology.

  Last year, inspired by nature, Naturex patented a new extraction process based on this phenomenon of "eutectigenesis" which mimics the intracellular environment. It consists of extracting the active compounds from the plant with the formation of a NaDES, a natural alternative solvent. Based on this process, they developed a new range of cosmetic products named "Eutectys™" (Figure I-45).

Figure I- 45 .

 45 Figure I-45. Logo of Eutectys™ product range.

Figure I- 46 .

 46 Figure I-46. Environmental footprints of olive leaf Eutectys™ and standard (conventional) extracts according to selected parameters.

  reasoned sourcing of plant material  Selection of alternative solvents, less harmful towards users and environment, but equally effective for extraction  Limitation of total energy consumption  Development of compact, robust and safe processes  Management and valorization of by-products generated during the process  Recovery of eco-extract with green values (non-denatured, bio-degradable and without contaminants).

II. 1 . 1

 11 Rosemary Rosemary (Rosmarinus officinalis L.) was provided by Naturex (Figure II-1). The batches used were collected in Morocco in 2012, 2013 and 2015. For rosemary used in CHAPTER III, initial moisture content was 8.93 ± 0.01 % and initial content in rosmarinic acid (RA) and carnosic acid (CA) was 0.21 % and 1.70 % respectively. For rosemary used in CHAPTER IV, initial moisture content was 8.33 ± 0.01 % and initial content in RA and CA was 0.91 % and 2.4 % respectively.

Figure II- 1 .

 1 Figure II-1. Rosemary (Rosmarinus officinalis L.) leaves.

Figure II- 2 .

 2 Figure II-2. Ginger rhizomes (a) and ginger press cake (b) used in the study.

1

 1 Computational method: COSMO-RS calculation

(II. 3 . 3

 33 ii) The second step relies on the statistical thermodynamics calculation. The polarization charge density was used for the quantification of the interaction energy of pair-wise interacting surface segments with regard to the most important molecular interaction modes, i.e. electrostatics and hydrogen bonding. The 3D distribution of the polarization charges σ on the surface of each molecule was converted into a surface composition function (σ-profiles). Such σ-profiles provided detailed information about the molecular polarity distribution. The chemical potential of the surface segment (σ-potential) was calculated from thermodynamics of the molecular interactions based on the obtained σ-profile. . In practice, the smiles formats of rosmarinic and carnosic acids were implemented in the software and both molecules were generated and added to the available database.All calculations were performed using the COSMOtherm X program (Version C30 Release 16.01). Various ethanol:water mixtures were modeled wherein the percentage of ethanol varied from 0 to 100 % with 10 %-increments. For each mixture, calculations were specifically conducted at ambient temperature (20 °C). The solvent screening option works similar to the solubility option and is based on the same thermodynamics calculations. It allows predicting the solubility of one solute in a list of solvents. The logarithm of the best solubility was set to 0 and all other solvents were ranked relative to the best one. A solvent with a log(x_solubility) (where x is mole fraction) value of -1.00 corresponds to a solubility decreased by a factor 10 compared to the best solvent. II.3.2 Experimental solubilities of RA and CA into various ethanol:water mixtures For convenience, experiments were performed at ambient temperature (20 °C) with high purity standards (97 % for RA and 98 % for CA). Various quantities of each standard were weighted into microtubes and a precise volume of each solvent mixture was added.Microtubes were vortexed (5000 rpm) for 3 min and centrifuged for 10 min (MiniStar silverline, VWR, France). Then a quantity of supernatant was sampled and diluted into methanol with 0.5 % of H3PO4 for CA and methanol:water 50:50 (v/v) for RA. Each experiment was performed in duplicate. Samples were subsequently injected into the HPLC system. Degradation study of CA The solubility of CA was investigated depending on the solvent and temperature. The standard was weighed and solubilized in 100 % ethanol, 50 % ethanol and 100 % water in order to reach the same concentration as in the extraction media. Resulting solutions were magnetically stirred (500 rpm) for 1 h under reflux (78 °C for 100 % ethanol, 82.2 °C for 50 % ethanol and 100 °C for 100 % water). However, since a gap exists between solvents' boiling points (until 20 °C between 100 % ethanol and 100 % water), experiments were also performed at 78 °C with 50 % ethanol and at 78 °C and 82.5 °C with 100 % water to assess the effect of temperature on compound stability. After experiment, samples were directly injected into the HPLC system. II.4 EXTRACTION PROCEDURES II.4.1 Conventional processes II.4.1.1 Heat reflux extraction (HRE) To assess the best solvent for extraction, rosemary leaves were submitted to reflux for 60 min with various solvents. The solvent was composed of ethanol:water mixture in different proportions: 0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 96:4 or 100:0 (v/v

[ 163 ]Figure II- 3 .

 1633 Figure II-3. Hydrodistillation apparatus.

Figure II- 4 .

 4 Figure II-4.

Figure II- 4 .II. 4 . 2 . 1

 4421 Figure II-4. Equipments assessed for the ultrasound and microwave assisted extraction study.

Figure II- 5 .

 5 Figure II-5. Bio-refinery-inspired process developed for the valorization of RA and CA from rosemary.

  Figure II-6. Flow sheet of processes used in the study for total valorization of ginger by-products. MHG: Microwave Hydrodiffusion and Gravity; UAE: Ultrasound assisted extraction; DW: Dry weight

Figure II- 7 .

 7 Figure II-7. Microwave Hydrodiffusion and Gravity: from laboratory (a) to pilot scale (b).

Figure II- 8 .

 8 Figure II-8. Ultrasound assisted extraction: from laboratory (a) to pilot scale (b).

1

 1 High performance liquid chromatography (HPLC-DAD) II.5.1.1 Rosmarinic, carnosic and ursolic acids Quantification of RA, CA and ursolic acid (UA) in rosemary extracts was conducted by HPLC (Agilent 1100, France) equipped with a diode array detector (DAD). Specific analytical procedures are described below.

II. 5 . 1 . 2 II. 5 . 3

 51253 Gingerols and 6-shogaolQuantification of gingerols (6-gingerol, 8-gingerol, 10-gingerol) and 6-shogaol in ginger extracts was done by HPLC (Agilent 1100, France) equipped with DAD. The method described below was developed and validated internally.The column used was a C18 column (5 µm, 4.6 mm x 250 mm, Advanced Chromatography Technologies ACE, Scotland). The mobile phase was composed of two solvents: (A) 100 % acetonitrile and (B) 100 % water with 0.05 % phosphoric acid (v/v). The gradient of solvent was used as follows: 0 minute, 45 % (A), 55 % (B); 5 min, 45 % (A), 55 % (B); 10 min, 50 % (A), 50 % (B); 20 min, 55 % (A), 45 % (B); 40 min, 90 % (A), 10 % (B); 45 min, 45 % (A), 55 % (B); 55 min, 45 % (A), 55 % (B). The flow rate was set at 1 mL/min. The column oven temperature was 20 °C and the run time was 30 min. 20 µL were injected. Gingerols and 6-shogaol were detected at a wavelength of 282 nm and quantified using external calibration with standards.II.5.2 Gas chromatography analysis (GC-FID)Aromatic profile of ginger EO was done by GC (Agilent 7890, France) equipped with flame ionization detector (FID). The method described below was developed and validated internally. The column used was a VF-5MS column (0.25 µm, 0.25 mm x 30 m, Agilent Technologies, France). The column temperature was 60 ° C for 1 minute, increased at 3 °C/min to 240 °C, and was kept at 240 °C for 5 min. Split ratio was 1:100 and helium flow rate was 1.1 mL/min with a constant flow. FID detection was performed at 250 °C. Identification was performed by corresponding individual standards retention times and the aromatic profiles were determined by comparison between relative areas on the chromatogram. Determination of total phenolic content (TPC) II.5.3.1 Principle

II. 5 . 4

 54 Oxygen radical absorbance capacity assay (ORAC) II.5.4.1 Chemical mechanism This method is a competitive method based on the fluorescence properties of fluorescein sodium salts (FLH) (Figure II-9).

Figure II- 9 .

 9 Figure II-9. Fluorescein sodium salt (FLH).

Figure II- 10 .

 10 Figure II-10. Peroxyradicals formation from AAPH (from [183]).

Figure II- 11 .Figure II- 12 .

 1112 Figure II-11. Protection of fluorescein elicited by an antioxidant.

Figure II- 13

 13 Figure II-13. DPPH • radical.

II. 5 . 6

 56 High performance thin layer chromatography (HPTLC) coupled to DPPH free radical scavenging activity measurement Ethyl acetate:glacial acetic acid:methanol:water in 60:15:15:10 (v:v:v:v) proportions was used as mobile phase. HPTLC was conducted on 20.0 x 10.0 cm plates composed of silica gel 60 F 254. Various rosemary extracts were diluted between 1.4 and 2.7 g/L and were deposited using a CAMAG Automatic TLC Sampler (CAMAG, Switzerland) equipped with a 25-μL syringe. The bands were 6 mm-long. Plates were developed in a CAMAG twin trough chamber (CAMAG, Switzerland). Humidity control was performed with MgCl2 (33 %) during 10 min and the chamber was previously saturated with mobile phase vapor for 20 min at room temperature. After development and drying in the chamber, the plates were immersed during 1 sec in a 0.05 % DPPH solution (0.1 g DPPH in 200 mL methanol), dried at room temperature and observed in a CAMAG UV cabinet (CAMAG, Switzerland) (Figure II-14).

Figure II- 14 . 8 (

 148 Figure II-14. HPTLC modules.

FOR

  EXTRACTION OF ROSMARINIC, CARNOSIC AND URSOLIC ACIDS FROM ROSEMARY M. Jacotet-Navarro, N. Rombaut, A.-S. Fabiano-Tixier, M. Danguien, A. Bily, F. Chemat, Ultrasound versus microwave as green processes for extraction of rosmarinic, carnosic and ursolic acids from rosemary, Ultrason. Sonochem. 27 (2015) 102-109. doi:10.1016/j.ultsonch.2015.05.006. CONTEXT Antioxidant extraction from rosemary have been hugely studied in recent years. Extraction selectivity is generally solvent-dependent and based on "like dissolves like" principle. However, few studies investigated extraction selectivity according to the process. In this context, it would be interesting to assess both intensification capacity and extraction selectivity of specific processes (ultrasound (US) and microwave (MW)) towards rosemary antioxidants. ABSTRACT US and MW as green processes are investigated in this study, focusing on the extraction selectivity towards antioxidant extraction from rosemary leaves. Due to its richness in valuable compounds such as rosmarinic (RA), carnosic (CA) and ursolic (UA) acids, rosemary is a reference matrix for extraction study. In this work, six alternative processes are compared: US (bath, reactor and probe), MW (reflux under MW, MW under nitrogen pressure and MW under vapor pressure). The main result of this study is that selective extraction can be achieved according to extraction techniques and therefore to the extraction process.

Figure III- 1 .

 1 Figure III-1. Chemical structures of major valuable compounds in rosemary.

1

 1 details the experimental conditions of the mentioned processes. Some extraction processes, particularly conventional ones, are sometimes accompanied by several drawbacks, such as the use of harmful solvents, degradation of compounds of interest due to high temperature, long extraction time, difficulty to implement or high economic and energetic costs. That way, during the last few years, concepts of "Green chemistry" and "green extraction" emerged [14,205]. Extraction processes have been studied to be more energy saving, safe for users and environmental friendly than yesterday, without reducing extraction efficiency. Intensification of extraction processes taking in account those different aspects should become a new challenge for the design of extraction processes.

  by the bath compared to the ultrasonic reactor and the probe. Compared to HRE, it can be noted that equivalent yields are achieved at 40 °C using UAE. MAE was performed at 70 °C and higher temperatures (boiling temperature, 125 °C and 150 °C). For these extractions (Figure III-2), increasing temperatures lead to an increase of the extraction yield, the highest yield (25.2 %) being reached at 150 °C. It is a classical observation in extraction that extraction yields increase with increasing temperatures. If the extraction yield gives an indication of a process performance, the composition of the extracts has to be studied to assess the selectivity of extraction.

Figure III- 2 .

 2 Figure III-2. Comparison of mass extraction yields according to HRE, maceration, ultrasound and microwave assisted extraction.

  factor impacting on the extraction of CA. Homogenization prior to extraction does not lead to an enhanced extraction for RA, CA and UA (Figure III-3), however, RA is more rapidly extracted.

Figure III- 3 .

 3 Figure III-3. Comparison of RA, CA and UA extraction from rosemary according to the process assessed.

Figure III- 4 .

 4 Figure III-4. Hypothesis of the conversion of carnosic acid into carnosol.

Figure III- 5 .IV. 1 INTRODUCTION

 51 Figure III-5. Selectivity towards RA acid or CA according to temperature and intensification technology.

Figure IV- 1 .

 1 Figure IV-1. Assessment of processes and analysis performed in the study.

  Experiments were carried out to determine RA and CA's solubilities in various ethanol:water mixtures (Figure IV-3). They were performed at ambient temperature for convenience. In both cases, the solubility tends to increase with the ratio of ethanol in the solvent. Interestingly, experimental solubilities appears to be well correlated with the theoretical values calculated by COSMO-RS, even though CA and RA were implemented as non-deprotonated acids. For CA, solubility dramatically raised from 0.1 g/L (0-20 %) to 423.4 g/L (100 % ethanol). For RA, solubility increases from 17.7 g/L (0 % ethanol) to 472.2 g/L (90 % ethanol), with a further decrease to 392.7 g/L in pure ethanol. Based on these results, 90-100 % ethanol was selected as the best solvent composition to solubilize simultaneously RA and CA (FigureIV-3). Hypothesizing that the extraction process is predominantly determined by solubility phenomena, we investigated whether or not pure ethanol is the best extraction solvent for these two antioxidants.

Figure IV- 3 .IV. 3 . 2

 332 Figure IV-3. Experimental solubilities of RA (a) and CA (b) in various ethanol:water mixtures.

Figure IV- 4

 4 (b)). In contrast, selectivity of extraction for CA purity increased when ethanol proportion increased (Figure IV-4 (c)), which can be tentatively ascribed to the good solubility of CA in ethanol. It is also worth noting, as shown in Table

  The purities of RA and CA (Figure IV-4 (b) and Figure IV-4 (c)) were combined with the mass extraction yields (Figure IV-4 (a)) to determine the quantities recovered from rosemary leaves (Figure IV-4 (b) and Figure IV-4 (c)).

Figure IV- 4 .

 4 Figure IV-4. Total yields of targeted compounds from rosemary leaves as a function of the ethanol:water ratio of the extraction solvent: Extraction yield (expressed in %) (a); RA content expressed in g RA/100 g extract and g RA/100 g leaves (b); CA content expressed in g CA/100 g extract and g CA/100 g leaves (c).

IV. 3 . 3

 33 Antioxidant activity of rosemary extracts obtained using various ethanol:water mixtures This work aims at determining not only the impact of the ethanol content on CA and RA extraction, but also on activities of the final extracts to get the highest reducing, radical scavenging and antioxidant properties. Specific activities of RA and CA were also evaluated. "CA-like compounds" are introduced here because CA is a thermosensitive molecule readily transformable under high temperature into CO and other CA derivatives [210,231,232] which still have antioxidant properties provided by the catechol group (ortho-diphenol) which is not affected. IV.3.3.1 Determination of the total phenolic content (TPC) through the reducing activity TPC was determined in the extracts using Folin-Ciocalteu method. Calibration curves (Figure IV-5 (a), insert) show that RA is 2.8 fold more reducing than CA. This can be partially explained by the fact that RA (Figure IV-4 (b)) encompasses two catechol groups exhibiting high reducing activity, whereas CA only bears one (Figure IV-4 (c)). From a

  Figure IV-5 (b) presents the ORAC values as a function of the percentage of ethanol.

  plateau also corresponds to extracts with high RA content (Figure IV-4 (b)), which could highlight a correlation between RA content in extracts and ORAC value. The same has been found by Walch et al. who suggested a correlation between ORAC and RA and its derivatives [235]. Beyond 40 % ethanol, the antioxidant activity decreased by almost 55 % with an increase of ethanol proportion.

Figure IV- 5 .

 5 Figure IV-5. Total Phenolic Compounds in the extracts (expressed in mmol RA eq/g extract dry weight) as a function of the percentage of ethanol in the extraction solvent (a); Antioxidant activity (ORAC value expressed in µmol Trolox equivalent (TE)/g extract dry weight) of the extracts as a function of the percentage of ethanol in the extraction solvent (b).

  Figure IV-6 (b). The decrease of ethanol ratio in extraction solvent leads to an increase of

Figure IV- 6 .

 6 Figure IV-6. DPPH scavenging activity (expressed in mmol RA eq/g extract) of the extracts as a function of the percentage of ethanol in the extraction solvent (a); HPTLC profiles of the extracts after immersion into DPPH as a function of the percentage of ethanol in the extraction solvent (b).

IV. 3 . 4

 34 Contribution of RA and CA to extract activityThis section aims at a better understanding of extract activity. It was noticed in the previous part that the activity of extracts and more particularly the free radical scavenging activity could be ascribed to other molecules than RA and CA-like compounds (Figure). In this context, it would be interesting to know the respective contributions of RA and CA on global activity of the extract. Therefore they were evaluated regarding TPC, DPPH and ORAC assays.Although it was demonstrated that RA and TPC profiles share the same evolution, RA has only a modest impact; its contribution to the TPC response accounts for less than 5-20 % (Figure IV-7 (a)). Until 40 % ethanol, the weight of RA on TPC response was much higher than the weight of CA-like compounds. The respective impacts were similar from 50 to 80 % ethanol. Beyond this threshold (80 %), the weight of CA-like compounds was much higher, since the study previously showed that the corresponding extracts were very low in RA and high in CA, and also because the overall TPC collapsed. The total weight from RA and CAlike compounds on TPC was kept constant from 0 to 40 % ethanol (~ 20-30 %), then increased beyond 40 % ethanol until pure ethanol (~ 45-65 %). From 0 to 40 % ethanol, two hypotheses can be put forward: (i) either, most of the reducing capacity of the extract toward Folin-Ciocalteu reagent is to be ascribed to molecules other than RA and CA-like compounds, (ii) or a strong synergistic action took place between CA and RA that boost their reducing activity from ~ 20-40 % of the TPC response (when isolated) to higher value % (when combined). Despite the observation of Figure IV-6 (b) suggests that the first hypothesis is more plausible, the second hypothesis was tested experimentally to detect any synergic effect between RA and CA standards in their reducing capacity toward Folin-Ciocalteu reagent.Each standard was diluted independently at different concentrations: 0.06, 0.125, 0.25 and 0.5 g/L. Solutions were then prepared with a mix of the two standards at the same concentrations: the first solution with 0.06 g/L of RA and CA each, the second with 0.125 g/L of RA and CA each, and so on. As shown in Figure IV-7 (b), no synergistic effect was observed between the two molecules: when mixed in solution, the total absorbance corresponds to the addition of the absorbances of each molecule taken separately. To the best of our knowledge, there are only two reports of a synergistic effect involving RA.Remarkably, in both studies, the investigated system was a lipid dispersion. Peyrat-Maillard et al. indeed showed synergistic combination between RA and quercetin, and between RA and caffeic acid, in aqueous dispersion of linoleic acid.[START_REF] Peyrat-Maillard | Antioxidant activity of phenolic compounds in 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidation: Synergistic and antagonistic effects[END_REF] More recently, it was found in

Figure IV- 7 .

 7 Figure IV-7. Relative weight of RA and CA on Total Phenolic Compounds (expressed in %) (a); Assessment of the combination effect of RA and CA in reducing capacity (b).

  -Ciocalteu method, the impact of RA and CA on the ORAC value of all extracts was calculated (FigureIV-8) and showed that they account for less than 50 % of the global response. Other compound(s) with free radical scavenging activity are thus supposed to exert a significant impact on the antioxidant activity of the extracts.

Figure IV- 8 .

 8 Figure IV-8. Relative weight of RA and CA on ORAC value (expressed in %).

Finally, similarly

  to TPC and ORAC, DPPH profile shares the same evolution that RA content in the extract, while the impact of RA on the global DPPH scavenging activity accounts for only 25-30 % (from 0 to 70 % ethanol, Figure IV-9 (a)) and even less than 5 % beyond 90 % ethanol. Considering CA-like compounds, global contribution on scavenging capacity increased with the proportion of ethanol, topping more than 90 % on total response with 100 % ethanol. This trend follows the amount of CA-like compounds in the extracts. The total weight from RA and CA-like compounds on DPPH scavenging capacity increased from ~ 30 to 98 % with the increase of ethanol proportion from 0 to 100 %. The contribution of other compounds than RA and CA-like compounds suggested by Figure IV-6 for polar extracts below 40 % ethanol was confirmed since no synergistic effect on the global DPPH scavenging activity was observed between RA and CA (Figure IV-9 (b)).

Figure IV- 9 .

 9 Figure IV-9. Relative weight of RA and CA on DPPH scavenging activity (expressed in %) (a); Assessment of the combination effect of RA and CA in DPPH scavenging response (b).

  -(O-acetyl)-b-D-glucuronide isomer I 503.0879 Luteolin -3'-(O-acetyl)-b-D-glucuronide isomer II 503.0886 10 Luteolin -3'-(O-acetyl)-b-D-glucuronide isomer III 503.0871

Figure IV- 10

 10 Figure IV-10. LC-DAD profiles of 100 % water and 30 % ethanol extracts and compounds identification by LC-MS.

Figure IV- 11 .

 11 Figure IV-11. Conventional industrial processes to recover CA in acetone (a), RA in 80 % ethanol (b) and RA in water (c).

3 ,

 3 we decided to perform a first extraction with 92 % ethanol at boiling point during 60 min to recover CA, followed by an extraction with much lower amount of ethanol at boiling point for 60 min to recover RA (Figure IV-12). The main objective is to recover separately maximal amounts of RA and CA from one batch of rosemary and in a single process.

Figure IV- 12 .

 12 Figure IV-12. Simplified bio-refinery-inspired process for the valorization of RA and CA from rosemary.

  TOWARDS A "DRY" BIO-REFINERY WITHOUT SOLVENTS OR ADDED WATER USING MICROWAVES AND ULTRASOUND FOR TOTAL VALORIZATION OF FRUITS AND VEGETABLES BY-PRODUCTS M. Jacotet-Navarro, N. Rombaut, S. Deslis, A.-S. Fabiano-Tixier, F.-X. Pierre, A. Bily, F.

Figure V- 1 .Figure V- 2 .

 12 Figure V-1. Effect of MW power on quantity of constituent water recovered by MHG.

Figure V- 3 .

 3 Figure V-3. Specific HPLC-DAD chromatogram of a ginger extract at 282 nm.

Figure V- 4 .

 4 Figure V-4. Evolution of extract's dry weight as a function of ultrasonic intensity (and power density).

Figure V- 5 .

 5 Figure V-5. Effect of US on extraction yield and gingerols and 6-shogaol content in the extracts.

V. 3 . 4

 34 Process assessment according to the six principles of green extraction A process assessment of the DBR developed in this work was performed and compared with a CBR composed of an HD step for the recovery of EO and an ethanolic extraction step for the extraction of antioxidants from ginger (Figure V-6). The bio-refineries were evaluated according to the six principles of green extraction developed by Chemat et al.



  1): percentage of valorized raw material from food processing industry (in %)  Solvent (Principle 2): (mass of ethanol) / (total mass of solvent used for the bio-refinery) (in %)  Energy (Principle 3): energy consumption for the bio-refinery of 1.150 kg of raw material considering extraction and evaporation steps based on the energy transfer equation [177] (in kWh)  Waste (Principle 4): (mass of waste) / (total mass of solvent + raw material used in the process) (in %)  Process (Principle 5): extraction duration for the bio-refinery (in min) Product recovery (Principle 6): (mass of final product recovered) / (mass of available product in the plant material)On Figure V-6, it is important to notice that for each principle, a value close to the center is a positive result whereas a value far from the center corresponds to a negative result.

Figure V- 7 .

 7 Figure V-7. Total valorization of ginger by-products using a bio-refinery concept.

  de ce travail de thèse ont été de mettre en oeuvre des procédés d'extraction alternatifs pour améliorer le taux d'extraction et les interactions solutés/solvants des procédés industriels existants tout en diminuant la durée totale, le nombre d'opérations unitaires, la consommation énergétique et l'impact global du procédé sur l'environnement ; de valoriser les co-produits d'extraction en produits à haute valeur ajoutée au vu des quantités conséquentes générées ; de remplacer les solvants pétroliers et dangereux pour les utilisateurs et l'environnement par des solvants alternatifs plus « verts » ; et enfin d'accompagner scientifiquement l'implémentation industrielle des améliorations de procédés définies précédemment. Afin d'apporter des réponses à ces problématiques, cette thèse a proposé trois principaux projets traitant de l'intensification de procédés par des technologies innovantes, la substitution de solvants nocifs pour l'Homme et l'environnement par des alternatives plus « vertes » et la valorisation de co-produits de fruits et légumes en produits à haute valeur ajoutée. En premier lieu, le Chapitre I a présenté une étude bibliographique sur l'éco-extraction des produits naturels. Ses six principes se référant à la matière première, au solvant, à la consommation énergétique, aux co-produits d'extraction, au procédé et à l'extrait final ont été mis en relation avec le principe d'intensification et pour chacun d'entre eux, un constat de la situation actuelle a été dressé. Ce chapitre a permis d'identifier les bonnes pratiques à mettre en oeuvre pour s'inscrire dans une démarche d'éco-extraction et a montré que l'adoption d'une telle démarche présentait un intérêt environnemental, économique et social. De plus, les différentes « success stories » développées pour illustrer chaque principe ont montré que l'éco-extraction ne se limitait pas à un seul type de matière première ou d'extrait mais pouvait se retrouver à la fois pour des applications agro-alimentaire, cosmétique et pharmaceutique. Enfin, cette partie a également souligné que certains aspects sont très matures et aboutis, comparés à d'autres qui restent encore au stade de recherche et développement. Cependant, cela permet de mieux appréhender de potentielles évolutions de la réglementation, notamment en ce qui concerne les solvants autorisés pour l'extraction. Le Chapitre II décrit l'intégralité des méthodologies expérimentales utilisées dans cette thèse, incluant les protocoles d'extraction ainsi que les méthodes d'analyse quantitative et qualitative. Dans la première partie de cette thèse (Chapitre III), le procédé d'extraction des acides rosmarinique, carnosique et ursolique à partir du romarin a été intensifié par l'usage d'ultrasons et de micro-ondes dans l'éthanol 90 %. Plusieurs procédés ultrasons et micro-ondes ont été étudiés et comparés aux reflux et macération conventionnels en termes d'efficacité et de sélectivité d'extraction, ainsi qu'en termes de consommation énergétique. Les résultats ont montré que l'usage de ces technologies alternatives permettait d'obtenir des résultats similaires ou améliorés comparé aux procédés conventionnels et qu'il était possible d'avoir une sélectivité d'extraction en fonction de la technologie d'intensification utilisée. En effet, l'usage des ultrasons à basse température (40 °C) a mené à une extraction préférentielle des acides carnosique et ursolique tandis que l'usage des micro-ondes à haute température a permis d'obtenir l'acide rosmarinique. De plus, l'utilisation des ultrasons et des micro-ondes pour l'extraction est apparu comme une alternative verte puisque la consommation énergétique de tels procédés a été réduite par rapport à celle des procédés conventionnels. Dans la deuxième partie de ce travail, l'effet du ratio en éthanol dans le solvant d'extraction a été évalué pour l'obtention d'extraits de romarin. Plus particulièrement, l'effet sur le rendement massique d'extraction, la composition (teneur en acides rosmarinique et carnosique) et les capacités réductrice, anti-radicalaire et antioxydante des extraits ont été étudiés. De plus, afin de mieux comprendre le phénomène de solubilisation intervenant lors de l'extraction, les solubilités des acides rosmarinique et carnosique ont été évaluées dans les différents mélanges éthanol:eau en utilisant un logiciel de prédiction (COSMO-RS) et ont été comparées aux solubilités expérimentales. Les résultats obtenus ont permis de conclure que le choix du solvant était crucial pour orienter l'extraction puisque le solvant pour lequel le rendement massique est optimal (éthanol 50-80 %) n'est pas le même que celui optimisant le rendement en actif (éthanol 30 % pour l'acide rosmarinique et éthanol 100 % pour l'acide carnosique), ni que celui optimisant l'activité de l'extrait (éthanol 30 %). Avant de choisir le solvant, il est donc nécessaire de déterminer quel paramètre on souhaite optimiser. Cette étude a également montré que l'éthanol 100 % était le meilleur solvant pour solubiliser à la fois l'acide rosmarinique et l'acide carnosique, ce qui démontre que l'extraction n'est pas qu'un phénomène de solubilisation. En effet, si la solubilité et la sélectivité d'extraction sont corrélées pour l'acide carnosique, ce n'est pas le cas pour l'acide rosmarinique qui est mieux extrait avec de l'éthanol 30 %. Ce résultat suggère donc que l'histolocalisation des composés d'intérêt dans la plante influence grandement leur taux d'extraction. L'étude a aussi montré que la teneur en acide rosmarinique et l'activité de l'extrait étaient corrélées, ce qui fait de ce composé un déterminant majeur de l'activité. La présence d'autres composés actifs affectant positivement l'activité globale de l'extrait a également été démontrée. Enfin, au vu des résultats obtenus dans l'étude, il a été possible de développer un concept de bio-raffinerie du romarin pour extraire successivement l'acide carnosique peu polaire et l'acide rosmarinique polaire en faisant varier le ratio en éthanol. Ce procédé a permis d'avoir des recouvrements en actifs de 82 % et de 71 % pour l'acide carnosique et l'acide rosmarinique respectivement. Audelà des aspects plus fondamentaux qu'elle évoque, cette étude a donc permis de montrer qu'il était possible d'obtenir séparément les deux principaux actifs du romarin en un seul procédé, tout en utilisant un solvant « vert » pour l'extraction. Ce résultat est positif puisqu'actuellement, deux procédés indépendants, dont l'un mettant en oeuvre de l'acétone, sont réalisés pour obtenir les acides rosmarinique et carnosique. Enfin, une troisième partie de cette thèse a été consacrée à la valorisation de coproduits de gingembre par un procédé inspiré de la bio-raffinerie. Une bio-raffinerie « sèche » sans solvant ni eau ajoutés et utilisant des technologies vertes a été développé et son bilan environnementale a été dressé. A partir du press cake de gingembre qui est un déchet de l'industrie des jus de fruits ont été obtenus une huile essentielle, un extrait riche en composés phénoliques et un résidu solide riche en fibres et en antioxydants. L'huile essentielle a été extraite par MHG (Microwave Hydrodiffusion and Gravity) et l'effet de la puissance microondes sur l'efficacité d'extraction et sur la qualité de l'extrait a été étudié. La puissance optimale a également été déterminée comme 1,6 W/g de matière première. Puis, le résidu solide de gingembre après traitement micro-ondes a été soumis aux ultrasons dans son eau de constitution pour extraire les composés phénoliques (gingerols et 6-shogaol). L'intensité ultrasonore (ou densité de puissance) a été optimisée pour maximiser les rendements d'extraction. L'usage des ultrasons à 16,7 W/cm 2 (ou 0,303 W/cm 3 ) a permis d'augmenter significativement le rendement massique d'extraction, cependant il n'a pas permis d'atteindre un taux de recouvrement d'actifs similaire à celui obtenu par une procédé conventionnel dans l'éthanol 75 %. La solubilité limitée des actifs dans l'eau a été un facteur limitant. Par contre, le résidu solide trouve une utilité pour sa teneur résiduelle en composés phénoliques et en fibres. Enfin, les résultats ont montré que l'empreinte environnementale de la bio-raffinerie « sèche » développée dans l'étude a été réduite par rapport à celle d'une bio-raffinerie mettant en oeuvre des procédés conventionnels. En résumé, ces travaux de thèse ont permis de montrer qu'il été possible :  D'intensifier le procédé d'extraction des composés d'intérêt du romarin par l'usage d'ultrasons et de micro-ondes, et d'obtenir une sélectivité d'extraction en fonction de la technologie utilisée ;  D'obtenir les deux principaux antioxydants du romarin en un seul procédé en utilisant des mélanges hydro-alcooliques plutôt que des solvants plus nocifs tels que l'acétone ;  De valoriser des co-produits alimentaires en produits à haute valeur ajoutée par un procédé inspiré de la bio-raffinerie sans solvant ni eau ajoutés. De manière plus générale, cette thèse a démontré que l'éco-extraction est un concept qui peut aisément être implémenté en industrie et qu'il incarne l'avenir du domaine de l'extraction végétale, auquel chaque acteur industriel devra adhérer à plus ou moins court terme. Les différents résultats obtenus dans cette thèse soulèvent cependant des questions qui pourraient faire l'objet de futures recherches et de perspectives pour ce travail:  La prise en compte de l'extraction comme un procédé complet (et non comme une opération unitaire) et par conséquent élargir la démarche de chimie verte aux étapes de purification d'actifs et de formulation de l'extrait ;  L'évaluation du potentiel des co-produits alimentaires et leur intégration dans un système d'économie circulaire ;  La mise en place d'un outil d'Analyse de cycle de vie spécifique à l'extraction pour quantifier et qualifier de manière plus standardisée l'impact environnemental global d'un procédé d'extraction.

Figure 1 . 25 Figure 2 . 26 Figure 3 . 27 Figure I- 1 . 27 Figure I- 2 . 28 Figure I- 3 . 29 Figure I- 4 . 35 Figure I- 8 . 36 Figure I- 9 . 41 Figure I- 11 . 42 Figure I- 12 . 50 Figure I- 17 . 53 Figure I- 18 . 56 Figure I- 19 . 58 Figure I- 20 . 65 Figure I- 24 . 66 Figure I- 25 . 66 Figure I- 26 . 68 Figure I- 27 . 68 Figure I- 28 . 69 Figure I- 29 . 72 Figure I- 30 . 73 Figure I- 31 . 78 Figure I- 33 . 79 Figure I- 34 . 80 Figure I- 35 . 82 Figure I- 36 . 85 Figure I- 37 . 86 Figure I- 38 . 87 Figure I- 39 . 88 Figure I- 40 . 90 Figure I- 41 . 92 Figure I- 42 . 95 Figure I- 43 . 96 Figure I- 44 . 97 Figure I- 45 . 100 Figure I- 46 . 101 Figure II- 1 . 104 Figure II- 2 . 105 Figure II- 3 . 109 Figure II- 4 . 110 Figure II- 5 . 113 Figure II- 6 . 115 Figure II- 7 . 117 Figure II- 8 . 118 Figure II- 9 . 121 Figure II- 10 . 122 Figure II- 11 . 126 Figure III- 1 . 130 Figure III- 2 . 135 Figure III- 3 . 136 Figure III- 4 . 137 Figure III- 5 . 140 Figure IV- 1 . 147 Figure IV- 3 .Figure IV- 4 . 152 Figure IV- 5 . 155 Figure IV- 6 . 158 Figure IV- 7 . 160 Figure IV- 8 . 161 Figure IV- 9 . 163 Figure IV- 11 . 164 Figure IV- 12 . 165 Figure V- 1 . 178 Figure V- 2 . 179 Figure V- 3 . 182 Figure V- 4 . 184 Figure V- 5 . 185 Figure V- 6 . 188 Figure V- 7 .

 1252263271272283294358369411142125017531856195820652466256626682768286929723073317833793480358236853786388739884090419242954396449745100461011104210531094110511361157117811891211012211126113021353136413751401147341525155615871608161916311164121651178217931824184518561887 Figure 1. Schéma expérimental suivi dans le chapitre III. ....................................................... 25 Figure 2. Schéma expérimental suivi dans le chapitre IV. ....................................................... 26 Figure 3. Schéma expérimental suivi dans le chapitre V. ........................................................ 27 Figure I-1. Types of compounds extracted from plant materials. ............................................ 27 Figure I-2. Principle of intensification. .................................................................................... 28 Figure I-3. Essential inputs and outputs on an extraction process related to the six principles of green extraction. ................................................................................................................... 29 Figure I-4. Paclitaxel. ............................................................................................................... 32 Figure I-5. (-)-α-bisabolol. ...................................................................................................... 33 Figure I-6. Artemisinin. ............................................................................................................ 34 Figure I-7. Sclareol. .................................................................................................................. 35 Figure I-8. Plant milking technology. (PAT plant milking©). ................................................. 36 Figure I-9. Scheme of microwave assisted hydrodistillation processing. ................................ 40 Figure I-10. MHG extraction processing. ................................................................................ 41 Figure I-11. Main categories of green solvents (adapted from [19,42]) .................................. 42 Figure I-12. Evolution of water dielectric constant regarding temperature and comparison with conventional solvents (from [43]). ................................................................................... 43 Figure I-13. Surfactant/hydrotrope structure. ........................................................................... 44 Figure I-14. Scheme illustrating the Critical Micellar Concentration. ..................................... 45 Figure I-15. Surfactant and hydrotrope behavior according to their concentration in aqueous solution. .................................................................................................................................... 45 Figure I-16. Determination of solubility sphere using Hansen Solubility Parameters. ............ 50 Figure I-17. Step calculation with COSMO-RS: (a) molecule emerged; (b) molecular surface; (c) energies of local surface interactions between σ-profiles of targeted molecules and two solvents (water, ethanol); (d) σ-potentials of targeted molecules and solvent. ........................ 53 Figure I-18. Assessment of the most energy-intensive industries (from [73]). ........................ 56 Figure I-19. Process optimization procedure (adapted from [74]). .......................................... 58 Figure I-20. Ways to valorize fatal heat from industrial processes (adapted from [73]). ........ 60 Figure I-21. Ultrasound frequency range. ................................................................................ 62 Figure I-22. Compression and rarefaction cycles induced by an ultrasound wave (from [61]). .................................................................................................................................................. 64

  La recherche et développement dans le domaine de l'extraction végétale s'est largement intensifiée ces dernières années en raison de l'intérêt croissant pour les ingrédients naturels. Que ce soit pour des applications agroalimentaires, cosmétiques ou pharmaceutiques, les plantes offrent un large panel de molécules d'intérêt qu'il est possible d'extraire par différents procédés. Avec les préoccupations environnementales et sociétales inhérentes au secteur industriel d'aujourd'hui, il est désormais nécessaire d'inventer et développer de nouveaux procédés d'extraction oeuvrant pour une chimie verte plus propre visà-vis de l'environnement et plus sûre vis-à-vis des utilisateurs et consommateurs. Il est donc question de réduire les temps de procédé, la consommation énergétique, la toxicité et la quantité de solvant utilisé, la quantité de déchets générés, et d'augmenter les rendements et la sélectivité d'extraction. Pour cela, il est possible d'intégrer dans les procédés des innovations technologiques, qu'elles soient relatives au solvant ou au type de procédé lui-même.

		INTRODUCTION GENERALE
	MeTHF	2-methyltetrahydrofuran
	MgCl2	Magnesium chloride
	MHC	Minimum hydrotropic concentration
	MHG	Microwave hydrodiffusion and gravity
	MS	Mass spectrometry
	MW	Microwave
	MWHD	Microwave hydrodistillation
	Na2CO3	Sodium carbonate
	NaDES	Natural deep eutectic solvents
	ORAC	Oxygen radical absorbance capacity
	PAH	Polycyclic aromatic hydrocarbons
	PBS	Phosphate-buffered saline
	PD	Power density INTRODUCTION GENERALE
	PEF	Pulsed electric fields
	PLE	Pressurized liquid extraction
	RA	Rosmarinic acid
	REACH	Registration, Evaluation and Authorization of CHemicals
	RED	Relative energy difference
	RMCD	Randomly methylated β-cyclodextrin
	DPPH• ROO•	Radical 2,2-diphényl-1-picrylhydrazyl Peroxyradicals
	DPPH-H SFE	2,2-diphényl-1-picrylhydrazyne Supercritical fluid extraction
	DW SFME	Dry weight Solvent-free microwave extraction
	EFSA SWE	European Food Safety Authority Subcritical water extraction
	EO TFA	Essential oil Trifluoroacetic acid
	ESI	Electrospray ionization
		-20 -

Les travaux de cette thèse intitulée « Intensification des procédés d'extraction du végétal. Procédés innovants et solvants alternatifs » s'intègrent complétement dans ces problématiques. Cette thèse industrielle est pilotée par l'équipe GREEN au sein de l'UMR408 INRA-UAPV et se déroule en collaboration avec l'entreprise Naturex, leader mondial de l'extraction végétale. Les principaux objectifs de ce travail sont d'une part d'intégrer des innovations technologiques dans les procédés d'extraction et de les confronter avec les techniques communément utilisées en industrie ; et d'autre part de mieux appréhender leur apport à l'échelle industrielle pour la production d'actifs végétaux. Plus particulièrement, il s'agit de :

Table I -

 I

		Molecular formula	Density	Boiling point	Specific heat capacity	Enthalpy of vaporization	logP	Dielectric constant (20 °C)	Safety
		/	/	° C	J/(mol.K)	kJ/mol	/	/	/
	Acetone	C3H6O	0.791	56.1	125.5	31.3	-0.02	20.7
	Chloroform	CHCl3	1.49	61.3	114.3	31.4	1.92	4.81
	Dichloromethane	CH2Cl2	1.33	40	102.3	28.6	1.38	8.93
	Diethyl ether	C4H10O	0.713	34.6	172.5	27.2	1.13	4.33
	Ethanol	C2H6O	0.789	78.5	112.4	38.6	-0.31	24.5
	Ethyl acetate	C4H8O2	0.897	77	170	31.9	0.89	6.3
	Hexane	C6H14	0.675	68.7	197.7	28.9	3.46	1.89
	Isopropanol	C3H8O	0.786	82.4	160.8	44.0	0.23	17.9
	Methanol	CH4O	0.792	64.5	79.5	38.3	-0.57	32.7
	Water	H2O	1.000	100	75.3	40.7	-1.38	80.1

1. Relevant properties of most common conventional extraction solvents.

  hydrodistillation (HD), of which general concerns are long extraction time, high water consumption, and compounds degradation. Actually, microwave (MW) heating is added to existing process (Figure I-9): since it occurs from the inside to the outside of plant material, it is no longer necessary to use solvent as heating media. The biomass can be directly placed in MW reactor without any water or solvent. Under MW heating, constituent water of plant material reach its boiling point (100 °C) and vaporize. Resulting vapors rich in EO rise and are condensed in a Clevenger-type apparatus. Finally, EO is recovered by gravity difference.

Table I -

 I 2. Temperature-pressure couples to keep water at liquid state (from [44])

Addition of surfactant Saturation of the interface Saturation of aqueous media until Critical Micellar Concentration (CMC) Formation of micelles Surfactant/hydrotrope concentration Apolar compound concentration

		Matrix	Analyte	Surfactant/ hydrotrope	Experimental conditions	Ref
		Sage Salvia miltiorrhiza Bunge	Cryptotanshinone, tanshinone	Triton X-100 (non-ionic)	0.8 mol/L surfactant 65 °C -10 min in water	[54]
	SURFACTANT	Olive mill wastewater	Antioxidants	Genapol-X080 (non-ionic)	5 % surfactant in water NaCl 5 % pH 2.5-3.5 50 °C -20 min 5 % surfactant	[55]
		Red flesh orange juice	Phenols, carotenoids	Tween-80 (non-ionic)	in water pH 2.5-3.5 NaCl 20 %	[56]
					55 °C -30 min
	HYDROTROPE	Black pepper Piper nigrum Sour orange Citrus aurantium L. seeds Coleus Forskohlii roots	Piperine Limonin Forskolin	Sodium n-butyl benzene sulfonate Sodium salicylate or sodium cumene sulfonate Sodium cumene sulfonate or p-sulfonate toluene	0.05 -3.4 mol/L hydrotrope in water 30 °C -2 h 2 mol/L hydrotrope in water 60 °C -6 h 2 mol/L hydrotrope in 20 -90 °C -3 h water	[57] [58] [59]

CMC RANGE

MHC Surfactant behaviour

Hydrotrope behaviour targeted compounds, one or other category must be selected. Table

I

-3 illustrates some example of surfactant/hydrotrope assisted extraction.

Table I -

 I 3. Examples of surfactant and hydrotropic extraction (adapted from[START_REF] Petigny | Chapter 7: Water as green solvent for extraction of natural products[END_REF]).

Table I -

 I [START_REF] Zhang | Microwave assisted extraction of secondary metabolites from plants: Current status and future directions[END_REF]. Source and properties of common bio-solvents (adapted from[START_REF] Sicaire | Solvants alternatifs et techniques innovantes pour l'éco-extraction des huiles végétales à partir de graines oléagineuses[END_REF]).I.3.3.3 Decision-making tools for solvent selectionWhen we have to develop a new process from scratch, it is often difficult to determine directly the best extraction solvent. Depending on the type of raw material and molecules of interest, a large range of potential candidates is available and it is impossible to test

	experimentally each of them without a preliminary selection. Number of experiment and time
	required to screen every solvent would be too much important. To assist the selection, it is
	possible to use computational methods based on chemical and thermochemical aspects. In
	extraction field, two methods have been particularly used in the last decade: Hansen and
	COSMO-RS approaches, which will be described in the following parts.
	I.3.3.3.1 Hansen Solubility Parameters (HSP)

0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 Hz -20 kHz AUDIBLE WAVES 20 kHz -10 MHz ULTRASONIC WAVES Power US

	20 kHz -1 MHz
	(I > 1 W.cm 2 )

< 16 Hz INFRASONIC WAVES Diagnostic US

		1 MHz -10 MHz
		(I < 1 W.cm 2 )
	LOW	HIGH
	frequency US	frequency US
	16 -100 kHz	100 kHz -1MHz

Table I -

 I

[START_REF] Maqsood | Phenolic Compounds and Plant Phenolic Extracts as Natural Antioxidants in Prevention of Lipid Oxidation in Seafood: A Detailed Review[END_REF]

. Factors influencing ultrasonic cavitation and extraction efficiency.

Higher value Negative value Lower value

	Food Type	Type of residues
	Cereals, grains rice, wheat, corn	Straw, stem, leaves, germ, husk, bran, fibres
	Edible oils	Press solids, oil cakes, oil and water emulsions, shell of seeds
	Fruits and vegetables

Stem, pits, seeds, peel, pulp, pomace, nonnutritive fibres

In major cases, despite they are considered as waste, food processing and extraction by-products still contain organic molecules with high nutritional value (such as antioxidants, proteins, dyes, vitamins or oils) or high energetic potential

[START_REF] Cherubini | The biorefinery concept: Using biomass instead of oil for producing energy and chemicals[END_REF][START_REF] Fernando | Biorefineries: Current Status, Challenges, and Future Direction[END_REF][START_REF] Federici | Valorisation of agro-industrial by-products, effluents and waste: concept, opportunities and the case of olive mill wastewaters: Valorisation of agro-industrial by-products, effluents and waste[END_REF]

. Plus, they constitute a low cost raw material and large volumes are available, which present specific economic and environmental interest for industrials.

  This part provides examples of processes and equipment in accordance with principle 5 specifications. A focus is done more particularly on reduction of unit operations number and process automatization.I.6.3.1 Elimination of unit operationsIn a whole extraction process, solvent elimination from both extract and spent plant residue after extraction is one of the longest stage. It is even longer and energy consuming if boiling point of solvent is high. Moreover, it may cause the degradation of sensitive compounds in final extract, particularly when too hard experimental conditions are applied.

Intensification of global process using innovative technologies  Reduction of the number of unit operations by deep study of the process  Development of more compact unit operations  Ensure the global safety and robustness of the process  Total control of the process and flux related I.6.3 Success stories Therefore, the question of solvent removal is a real concern in current extraction field: it may result in a loss of final extract quality, but it is nevertheless a necessary step, particularly when extraction is performed with organic solvents. However, in certain cases, some alternative solutions can be adopted to skip this step, particularly:  Using solvent which can be removed directly after extraction process without concentration step;  Using solvent that forms part of final extract formulation. Plant extraction with supercritical CO2 as solvent is a perfect example to illustrate the first solution. As shown in Figure I-36, CO2 is gaseous at atmospheric pressure. Therefore,

after extraction under supercritical conditions (Tc=31 °C; Pc=73.8 bar), pressure is brought back to atmospheric level, and it results in direct removal of gaseous CO2 from the extract

[START_REF] Herrero | Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review[END_REF]

. Instantaneously, final extract is safe, exempt from any residual solvent and ready for further purification or formulation steps. As an example, valuable products extraction from rosemary and ginger (matrices of main interest in this thesis) using supercritical CO2 is hugely reported in current literature, particularly the recovery of EO, oleoresin or low polarity antioxidants

[START_REF] Ibañez | Subcritical Water Extraction of Antioxidant Compounds from Rosemary Plants[END_REF][START_REF] Herrero | Sub-and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review[END_REF][START_REF] Badalyan | Extraction of Australian ginger root with carbon dioxide and ethanol entrainer[END_REF][START_REF] Zancan | Extraction of ginger (Zingiber officinale Roscoe) oleoresin with CO2 and co-solvents: a study of the antioxidant action of the extracts[END_REF][START_REF] Genena | Rosemary (Rosmarinus officinalis): a study of the composition, antioxidant and antimicrobial activities of extracts obtained with supercritical carbon dioxide[END_REF][START_REF] Tena | Supercritical Fluid Extraction of Natural Antioxidants from Rosemary: Comparison with Liquid Solvent Sonication[END_REF][START_REF] Carvalho | Supercritical fluid extraction from rosemary (Rosmarinus officinalis): Kinetic data, extract's global yield, composition, and antioxidant activity[END_REF]

.

Table I -

 I

		Conventional Soxhlet	Ankom XT15 extractor
	Extraction time	≤ 8 h	30 min -1 h
	Temperature	under boiling point	90 °C
	Pressure	atmospheric	under pressure
	Number of sample per batch	1	Up to 15
	Extraction yield determination	weighting final extract	by weight difference of raw material before/after extraction
	Possibility to determine final extract composition	yes	no
	boiling solvent for an effective extraction of active compounds (1-). The choice of solvent and
	extraction duration is free. After extraction, solvent level is decreased below extraction
	thimble. A part of solvent is collected in recovery tank (2-) and the other part continues to
	flow through the sample to complete previous extraction step (3-). Then, solvent is completely

9 compares the performances of conventional Soxhlet extraction and extraction with Ankom XT15 extractor for the determination of crude fat and oil content. In conclusion, this equipment is efficient, compacted, sure, well-controlled and enables to save time, money and place, and therefore in accordance with principle 5 specifications. The main disadvantage is that final extracts are not recovered at the end of the process, which avoid potential composition determination. As another example, VELP® society developed an automatic solvent extractor (SER 158) to extract a wide range of plant materials. Processing steps of such equipment are presented in Figure I-39. First of all, sample is placed in extraction thimble and immersed in collected in recovery tank (4-). Finally, heaters are switched off and glassware is lifted to prevent burning of dried extract (5-).

Table I-9. Comparison between conventional Soxhlet and Ankom XT15 extractor for the determination of crude fat content.

Figure I-39. Extraction progressing with SER 158 Solvent AutoExtractor.

Table I -

 I [START_REF] Keil | Modeling of process intensification[END_REF]. Examples of microwave assisted extraction to recover essential oil from various plant materials. However, they may be stored and transported in a third class of liquid phase named natural deep eutectic solvents (NaDES). By definition, a NaDES is a mixture of compounds, in specific proportions, which presents a lower melting point than any of the individual components. The mixture thus becomes liquid at room temperature.

		Microwave assisted process	Solvent	Reference
	Rosemary	Microwave assisted hydrodistillation (MAHD)	Water	[158]
	Fennel (Foeniculum vulgare)	Microwave hydrodistillation (MWHD)	Water	[159]
	Lavender	Microwave assisted steam distillation (MASD)	Steam	[160]
	Calamintha nepeta (L.) Savi	Solvent-free microwave extraction (SFME)	/	[30]
	Grapefruit peel	Solvent-free microwave extraction (SFME)	/	[161]
	Citrus	Microwave accelerated distillation (MAD)	/	[162]
	Rosemary	Microwave hydrodiffusion and gravity (MHG)	/	[33]

I.7.3.2 High resolution extract from plant core: Eutectys™ products Plant materials are a huge source of very various active molecules synthetized at the very core of the plant cells. Some of these metabolites are neither hydrosoluble nor liposoluble.

  Considered as 100 % natural, Eutectys™ extracts are Ecocert and Cosmos approved and easily bio-degradable (OECD301b). Miscible in water and glycols, they are also very easy to formulate. Plus, they are completely safe as established by a toxicological expert according to European regulation (EC) n°1223/2009). In terms of regulation, Eutectys™ extracts are REACH compliant, and authorized in Europe, USA and China (IECIC 2014).

	Products	Improved chemical profile Improved properties
	Saffron flower Eutectys™	Richer flavonoid composition	Anti-aging (+ 91 %) Radiance and whitening
	Sea fennel Eutectys™	Higher content in phenolic compounds	Radiance and whitening
	Rose of Jericho Eutectys™	Higher content in phenolic compounds	Radiance and whitening
			Anti-wrinkle, regenenatory,
	Olive leaf Eutectys™	+ 400 % oleuropein	and firming (stimulation of collagen synthesis x 17)
			Photo-protective (x 3.7)
	Horsetail Eutectys™	+ 18 % phenolic acids	Soothing (x 5) Antioxidant (+ 61 %)
	Rosemary Eutectys™	Rosmarinic acid content x 120	Antioxidant (+ 100 %)
	Finally, last but not least, the environmental footprint related to their production is reduced
	compared to those of conventional hydro-glycerin extract (Figure I-46). Therefore,

Table I-11, these new products present superior phytochemical

profiles and improved performance compared to the corresponding conventional hydroglycerin extracts.

Eutectys® extracts are fully in line with the principles of green chemistry and can be considered completely as "eco-extracts".

Table I -

 I

11. Improved chemical profiles and properties of Eutectys™ extracts compared to the corresponding hydro-glycerin extracts.

  allows the recovery of a juice composed of EO and constituent water. In all extraction experiments, EO was collected and analyzed. Constituent water and GPMHG were recovered and stored at 4 °C before use. Each experiment was performed in duplicate.

		Ginger rhizomes (GR)	HPLC
		Pressing		Juice
		II.4.3.2.2 Ultrasound Assisted Extraction (UAE)
		Ginger press cake (GP)	HPLC
		Essential 20 g of GPMHG were placed in a double jacket reactor with 500 g of constituent
	Water	Essential oil water. The whole was submitted to US (1 kW, UIP 1000 hdT, Hielscher Ultrasonics GmbH, 6 h Intrinsic GC [0.6 -1.8 W/g] HD oil GC MHG
					water	HPLC
			MHG press cake solid residue (GPMHG)	HPLC
		Ethanol: water 75:25	Maceration 1 h	UAE [4.4 -16.7 W/cm²] 1.5 h	%DW
					Phenolics
			Filtration	Filtration	Evaporation	6-gingerol 8-gingerol
					10-gingerol	HPLC
					6-shogaol
		Evaporation	Fibres
			Phenolics
			6-gingerol
			8-gingerol
			10-gingerol
			6-shogaol

HPLC

MHG process

Table III -

 III 1. Examples of extraction conditions to recover RA, CA and CO from rosemary.III.2 MATERIALS AND METHODSRosemary (Rosmarinus officinalis L.) was provided by Naturex. The batch used was collected in Morocco in 2013 and previously hydrodistillated by the supplier. Only leaves were used and were ground for 10 s before extraction using a coffee grinder (Severin, France).

	III.3 RESULTS AND DISCUSSION
	III.3.1 Comparison of extraction processes in terms of mass extraction yields
	Extraction yields obtained by heat reflux extraction (HRE), maceration, UAE and
	Initial moisture content was 8.93 ± 0.01 % and initial content in rosemary in RA and CA is microwave assisted extraction (MAE) are presented in Figure III-2. Regarding HRE
	0.21 % w/w and 1.70 % w/w respectively. extractions, it can be identified that most of the extraction is achieved within 30 min.
	Increasing the duration of HRE up to 5 h does not lead to a drastic increase of the extraction Ten different extraction processes were applied in this study: four conventional yield (20 % against 19 % for 5 h and 30 min extraction duration respectively). Moreover, processes (reflux 30 min, reflux 5 h, grinding 3 min followed by reflux 30 min, and adding a preliminary step of homogenization prior to HRE does not improve significantly the maceration) and six innovative (US bath, US reactor, US probe, reflux under MW, MW under yield (18.8 ± 0.2 % and 19.0 ± 0.5 % respectively). Maceration at 40 °C for 30 min results in
	a much lower extraction yield (10.0 ± 0.3 %). These differences in yield between HRE and
	maceration are attributed to the temperature difference during extraction.

nitrogen pressure and MW under vapor pressure). Those processes are detailed in CHAPTER II and illustrated in Figure II-4.

All the extractions were performed using a solid/liquid ratio of 1/20 (m/v). The extraction solvent was ethanol/water mixture in a proportion of 90/10 (v/v). After extraction, the solvent was separated from the matrix by filtration to vacuum using a filter paper. The extract was concentrated until dryness by solvent evaporation under vacuum (Laborota 4001, Heidolph, Germany).

For UAE, extraction temperatures were maintained at 40 °C. It can be identified that similar extraction yield are obtained for extraction performed with the US reactor and for the US probe (18.1 ± 2.3 % and 18.8 ± 2.2 % respectively). Lower yields are obtained with the US bath (13.1 ± 0.1 %). Those results may be explained by a low ultrasonic power delivered

  -2). Globally, our results indicate that higher pressure and intensification through MW favors a higher ratio of CO compared to CA.

HRE: Heat reflux extraction; US: ultrasound; MW: microwave; DW: dry weight

Table III -

 III 2. Purities of carnosic acid and carnosol in the extracts obtained by the different processes.An energy consumption monitoring of the different experiments was performed.Table III-3 indicates the measures obtained per process. In all cases the evaluation was performed on 10 g of rosemary leaves and 200 mL of solvent. It appears clearly that 5 h reflux is the most energy-consuming technique (850 kWh/kg extract) and consequently the process with the highest carbon emissions associated (680 kg CO2/kg extract). It is mainly due to the long extraction duration (5 h). US processes applied during 30 min present the lowest values compared to MW processes and HRE: US probe resulted in an energetic consumption of 23 kWh/kg extract and 19 kg CO2/kg extract. Therefore, at laboratory scale, this process appears as the best compromise between yield and energy consumption. MW treatments also show reduced values compared to HRE, with few differences between MW processes.

	III.3.4 Energy consumption
			Purity of compounds in extracts
	Extraction process	Experimental conditions (temperature -extraction duration)	CA (%)	Carnosol (%)
	HRE	78 °C -30 min	7.75 ± 0.01	2.22 ± 0.02
	HRE	78 °C -5 h	6.38 ± 0.08	2.10 ± 0.01
	Grinding + HRE	78 °C -30 min	5.32 ± 0.58	2.09 ± 0.07
	Maceration	40 °C -30 min	8.41 ± 0.71	2.50 ± 0.12
	US bath	40 °C -30 min	7.73 ± 0.63	2.26 ± 0.16
	US reactor	40 °C -30 min	6.27 ± 0.92	2.02 ± 0.27
	US probe	40 °C -30 min	8.21 ± 0.00	2.37 ± 0.03
	Ultraclave 100bar	70 °C -30 min	6.45 ± 0.02	2.24 ± 0.03
	Reflux under MW	78 °C -30 min	6.19 ± 0.49	1.93 ± 0.10
	MW under pressure	125 °C -30 min	2.53 ± 0.17	3.36 ± 0.07
	(vapour pressure)	150 °C -30 min	2.17 ± 0.66	2.04 ± 0.02

This energetic assessment was carried out at laboratory scale using an electrical meter, allowing a comparison on the basis of the sole process. For upscaling and industrial considerations, a Life Cycle Assessment (LCA) could be established to obtain the energetic and environmental profiles of different products or processes

[203,[START_REF] Roy | A review of life cycle assessment (LCA) on some food products[END_REF]

. That way, LCA could be a tool for industrial decision-making since it could determine which process is the most eco-friendly and economical. HRE: Heat reflux extraction; US: ultrasound; MW: microwave

Table III -

 III 3. Energy consumption and carbon emissions of the different extraction processes.This study was carried out to compare different processes for extraction of RA, CA and UA from rosemary leaves. The main conclusion is that selective extraction of RA and CA can be achieved by modification of the extraction technique and procedure. The use of intensified extraction processes at different extraction temperatures enabled to achieve similar yields compared to conventional extraction processes (HRE and maceration). It has been demonstrated that CA and UA extraction is enhanced using US processes at lower temperature whereas MW are more adapted to extract RA at higher temperature (Figure III-5). Moreover, this study revealed that US and MW technologies are good alternatives to conventional processes regarding energy consumption and carbon emissions at laboratory

	III.4 CONCLUSION
	Extraction process	Experimental conditions (temperature -extraction duration)	Energy consumption (kWh/kg extract)	Carbon emissions (kg CO2/kg extract)
	HRE	78 °C -30 min	94	75
	HRE	78 °C -5 h	850	680
	Grinding + HRE	78 °C -30 min	94	75
	Maceration	40 °C -30 min	79	63
	US bath	40 °C -30 min	15	12
	US reactor	40 °C -30 min	39	31
	US probe	40 °C -30 min	23	19
	Ultraclave 100bar	70 °C -30 min	154	123
	Reflux under MW	78 °C -30 min	85	68
	MW under vapour	125 °C -30 min	171	137
	pressure	150 °C -30 min	157	125

scale. Further research are required to investigate the choice of the most appropriate technology for scale up and industrialization

[START_REF] Mason | The extraction of natural products using ultrasound or microwaves[END_REF]

.

  30 % ethanol appeared as the best extraction solvent to recover RA. The highest yield for CA was obtained with 70 % ethanol (~2.2 g CA/100 g leaves) even though quite similar yields were found with 50 and 60 %. Table IV-1. Degradation rate of carnosic acid according to the solvent and the temperature.

	Importantly, actives recovery from dried leaves for RA and CA were 100 % (at 30 % ethanol)
	and 91 % (at 70 % ethanol), respectively. Therefore, considering global extraction yields, a
	ratio ranging from 50 % ethanol to 80 % ethanol gives highest mass extraction yields (26.3-
	27.7 %) and total content in targeted compounds (3.0-3.1 g/100 g leaves).
			Degradation rate (%)
		78 °C	82.5 °C	100 °C
	100 % water	45.6 ± 12.2	70.1 ± 6.4	97.8 ± 3.1
	50 % ethanol	2.3 ± 0.3	0.5 ± 0.1	/
	100 % ethanol	0.2 ± 0.3	/	/

IV.3.2.2 Is plant extraction all about solute solubility in the solvent?

  Table IV-2. The percentage of recovery corresponds to the amount of compound extracted regarding the initial amount available in the plant.The first extraction enables to recover 82.0 ± 6.6 % of available CA in initial rosemary. It is an encouraging result because it corresponds to the amount currently extracted at industrial level with acetone. Regarding RA, the amounts extracted during the first and the second extraction are approximately 20 % and 50 %, respectively, reaching a total recovery of 70 %. From this result, improvement must be performed at two levels:  Reduction of RA recovery during the first extraction  Increase of RA recovery during the second extraction To deal with this problematic, extraction time and temperature were varied and their influence on extraction was assessed.

	3.5.1 Development of bio-refinery process IV.3.5.1.1 Preliminary assay For the extraction of CA, 92 % ethanol was selected as solvent since higher content of ethanol (96 % or 99 %) is not up-scalable at industrial level. Actually, current solvent recycling conditions enable to reach maximally 92 % ethanol in the final recycled solvent. Laboratory tests were therefore carried out directly with this ratio of solvent. CA extraction was performed firstly since CA is a thermolabile compound which might be degraded if a first extraction with water is performed. After the first extraction to recover CA, water was added to the rosemary residue, and a second extraction was carried out to recover RA. The results of 1h Boiling point 20 % ethanol 1h Boiling point Lipophilic extract (rich in CA) Hydrophilic extract (rich in RA) 8 % ethanol 1h Boiling point Process Experimental parameters CA recovery (%) RA recovery (%) 1 st extraction 92 % ethanol, 60 min, boiling point 82.0 ± 6.6 21.4 ± 1.0 this first experiment are presented in 92 % ethanol 2 nd extraction 20 % ethanol, 60 min, boiling point Not analyzed 50.3 ± 2.6

Table IV -

 IV 2. Preliminary results regarding the consecutive recovery of CA and RA from rosemary. Others parameters were kept constant compared to the preliminary test. In a second experiment, to assess the influence of extraction time on RA recovery, the strategy adopted was reducing the first extraction duration to 30 min and increasing the second one to 90 min.Results of both experiments are presented in Table IV-3 and Table IV-4.As wanted, decreasing temperature and duration of the first extraction caused the decrease of RA recovery from 21.4 % to 5.1 % and 10.6 %, respectively. However, CA recovery was also affected since the yield was decreased from 82 % (in preliminary experiment) to 67.6 % (lower temperature) and 71 % (lower extraction time). CA being the most important compound to valorize, the decrease of extraction temperature and time was abandoned. Table IV-3. Impact of temperature on CA and RA recovery.

	IV.3.5.1.2 Impact of extraction time and temperature Previous work about RA and CA extraction demonstrated that CA was extracted quickly than RA in the solvent, and that CA can be efficiently extracted at medium-low temperature contrary to RA which needs higher temperature [221]. It suggests that decreasing temperature or duration of the first extraction in our case might decrease RA recovery, without affecting CA extraction efficiency. Therefore, a first experiment consisted in decreasing the first extraction temperature to Experimental parameters CA recovery (%) RA recovery (%) 1 st extraction 92 % ethanol, 60 min, 65 °C 67.6 5.1 2 nd extraction 20 % ethanol, 60 min, boiling point Not analyzed 54.0 Process Experimental parameters CA recovery (%) RA recovery (%) 1 st extraction 92 % ethanol, 30 min, boiling point 71 10.6 65 °C. Process 2 nd extraction 20 % ethanol, 90 min, boiling point Not analyzed 48.2

Table IV -

 IV [START_REF] Zhang | Microwave assisted extraction of secondary metabolites from plants: Current status and future directions[END_REF]. Impact of extraction time on CA and RA recovery.The performance of a second cover enabled to recover 20.5 ± 0.1 % more RA. Therefore, in the global process, 82.0 % of available CA and 71 % of available RA were recovered separately in two independent extracts. Total amount of RA recovered in the whole process is about 92 %, which means that plant material was almost completely drained at the end of the bio-refinery. The only negative thing concerns the RA extracted with CA during the first extraction. However, it is not excluded that a further purification step performed on the extract permits its recovery and valorization.

	Process	Experimental parameters	CA recovery (%) RA recovery (%)
	1 st extraction 92 % ethanol, 60 min, boiling point	82.0 ± 6.6	21.4 ± 1.0
	2 nd extraction 1 st cover	20 % ethanol, 60 min, boiling point	Not analyzed	50.3 ± 2.6
	2 nd extraction 2 nd cover	8 % ethanol, 60 min, boiling point	Not analyzed	20.5 ± 0.1
	Regarding the second extraction, increasing the duration from 60 min to 90 min did
	not enhance RA recovery: for both extraction durations, approximately 50 % of available RA
	was recovered at the end of process. Therefore, we chose to perform two covers for the
	second extraction, in order to see if RA recovery might be maximized in this way. Results are
	summarized in Table IV-5.

Table IV -

 IV 5. Optimal recovery of CA and RA from rosemary in three consecutive steps. of residual solvent) was also reduced to almost zero: only one stripping step is needed with the bio-refinery (and very few amounts of ethanol have to be removed as the solvent is 8 % ethanol) against two for existing process (one to remove acetone and one to remove 80 % ethanol). Solvent removal is often very energy consuming, particularly when the heat capacity Cp and the enthalpy of vaporization ΔHvap are high.Globally, the challenge of rosemary bio-refinery was met successfully and we achieved to extract selectively CA and RA by varying the amount of ethanol in the solvent.Extraction of both CA and RA was performed in one single process from one single batch of rosemary, what makes the process economically and environmentally efficient.

		EXISTING PROCESSES		BIO-REFINERY
	CA extraction	RA extraction (1)	RA extraction (2)	CA extraction	RA extraction
	IV.3.5.2 Comparison with existing process The bio-refinery developed in this study is compared with existing industrial processes in Table IV-6 for the recovery of CA and RA. The bio-refinery appears as an efficient innovative process which is in accordance with the six principles of green extraction presented in CHAPTER I:  Principle 1 (raw material): the quantity of raw material needed to recover both CA and RA is divided by two, since both compounds are extracted in one single process from the same batch of rosemary leaves.  Principle 2 (solvent): for the extraction of CA, acetone was replaced by 92 % ethanol, which is greener and safer for users and environment.  Principle 3 (energy): extraction duration was drastically reduced with the bio-refinery (3 h against 6 h 30-7 h with existing process) and consequently it would result in a decrease of energy consumption. Moreover, energy consumption related to spent raw material end of the process as rosemary leaves were reused to obtain RA with a second extraction.  Principle 5 (process): extraction duration was drastically reduced with the bio-refinery as well as the number of unit operations, particularly with the elimination of rosemary leaves stripping after CA extraction.  Principle 6 (eco-extract): active recovery with the bio-refinery was quite acceptable with 82 % recovery for CA and 71 % recovery for RA from one single batch of rosemary leaves. CA and RA extracts can be considered as organic since hydro-alcoholic mixtures were used as solvent. Quantity of raw material 100 kg 100 kg 100 kg Solvent Acetone 80 % ethanol 100 % water Volume of solvent 2000 L 2000 L 3000 L Extraction duration 2 h 5 h 4 h 30 Active recovery 90 % 75-80 % 90 % Green waste > 100 kg > 100 kg > 100 kg stripping (removal  Principle 4 (by-products): CA extraction process did not generate any green waste at the Stripping of residual rosemary Yes Yes No	100 kg 92 % ethanol 1000 L 1 h 82 % 0 kg No	0 kg 20 % ethanol 8% ethanol 1000 L 2 h 71 % > 100 kg Yes (very few amount)

Table IV -

 IV [START_REF] Maqsood | Phenolic Compounds and Plant Phenolic Extracts as Natural Antioxidants in Prevention of Lipid Oxidation in Seafood: A Detailed Review[END_REF]. Comparison between the bio-refinery and existing processes for the recovery of CA and RA from rosemary.IV.4 CONCLUSIONThis study shows how the solvent choice can be crucial for extraction since the solvent composition for which the highest recovery of targeted compounds is obtained does not necessarily gives the highest mass extraction yield nor the most active extract. Therefore, different solvents have to be selected depending on whether the extract performance is prioritized or a high mass extraction yield or a specific content in a targeted compound.Whereas highest mass extraction yield was obtained with 50-80 % ethanol, considering selectivity of extraction, RA was preferentially extracted with ethanol 30 %, and CA with pure ethanol. Furthermore, COSMO-RS predictions and experimental solubilities gave 100 % ethanol as the best solvent to solubilize both RA and CA. If solubility and selectivity were correlated for CA, it was not the case for RA, demonstrating that extraction is not all about solubilization and suggesting that the antioxidant histolocalisation strongly influences their extraction rates. Finally, the best performance of extract in terms of reducing, free radical scavenging and antioxidant activities was reached with ethanol 30 %, which is also the best conditions to recover high amounts of RA. At first sight, it would mean that RA content is a prime determinant of the global antioxidant/reducing performance of the extracts, while a

	more subtle observation reveals that other antioxidants are concomitantly present with RA
	and positively affect the global response. Taken together, these data point at crude rosemary
	extracts obtained with 0-30 % ethanol as promising antioxidant candidates for polar
	applications such as beverages.

  3 RESULTS AND DISCUSSION V.3.1 Dry extraction of essential oil from ginger press cake by MHG In the concept of DBR developed in this study (Figure II-6), MHG was chosen as a"green" process for the recovery of EO and constituent water from GP, as no solvent had to be added for extraction. MHG allows direct extraction of a juice composed of EO and constituent water. Both compounds were therefore extracted at the same time and further separated by gravity due to density difference. MW extraction of EO using "constituent water" may occur by a mechanism based on the influence of molecules polarity. EO contain organic compounds that strongly absorb MW energy such as oxygenated monoterpenes. MW interact with organic molecules present in the glands and vascular systems. Thus, such systems undergo a dramatic expansion, with subsequent rupture of the tissue, allowing the EO to flow towards the gland layer. Compounds with high and low dipolar moments could be extracted in various proportions by MW extraction. Organic compounds that have a high dipolar moment will interact more vigorously with MW and can be extracted more easily in contrast with aromatic compounds, which have low dipolar moments. constant at 100 °C; (iii) finally temperature presents an inflection point and begins to increase beyond 100 °C. This last stage is considered as the beginning of thermal degradation, which is accompanied by the burn of biomass submitted to MW.

	The increase in MW power from 0.6 W/g to 1.8 W/g led to the same final volume of
	constituent water and EO extracted from GP (1 ± 0.1 mL of EO and 300 ± 10 mL of
	constituent water). As it can be noticed in Figure V-1, the increase of MW power from
	0.6 W/g to 1.8 W/g enabled a considerable reduction of extraction time as well: 83 min
	against 20 min for 0.6 W/g and 1.8 W/g respectively. Therefore, the time needed to recover
	the condensate composed by EO and constituent water was directly dependent on MW power
	as the former increased with the latter.
	V.3.1.1 Impact of microwave power on MHG extraction efficiency of essential oil and
	constituent water
	Several powers were assessed in order to evaluate the impact of MW power on
	extraction efficiency of EO and constituent water from GP. Literature reports that MHG is
	optimally used with a power of 1 W per gram of plant material [172]. Yet, this aspect can be
	discussed because of the large variety of plant material which has probably not the same
	behavior regarding MW energy. In this study, an assessment of different MW powers was
	thus performed to extract as quickly as possible constituent water and EO from GP.
	MW power was varied from 0.6 W/g to 1.8 W/g of GP. Global volume of water and
	EO recovered was measured at different extraction durations (Figure V-1). The low volume
	of EO extracted did not allow an accurate measurement of EO extraction kinetics. Extraction
	was stopped just before thermal degradation of GP. The beginning of thermal degradation was

determined performing a temperature monitoring into the press cake. As shown in Figure V-2, during MW heating, (i) temperature into the biomass firstly increases linearly -more or less quickly depending on MW power-until 100 °C (boiling point of water); (ii) then temperature remains

Table V -

 V It can be noticed as well that MW power had not any effect on EO extraction yields as 0.2 g EO/100 g GP were recovered in all cases. MHG extraction of EO from GP appeared as less efficient than HD of GP, however this result is not very accurate since the design of glassware in the MW laboratory oven provided to recover totally the EO extracted

1 summarizes the results regarding extraction yields and composition of EO and phenolics obtained for GR, GP and GPMHG. The first part of the table refers to the results obtained regarding EO. Extraction yields and aromatic profiles were compared between EO obtained by HD of GR and GP (Table V-1, first and second columns), and EO obtained by MHG treatment of GP at different powers (Table V-1, third to ninth columns).

First of all, extraction of EO from GP by HD was more efficient than extraction of EO from GR (0.3 g EO/100 g GP and 0.2 g EO/100 g GR). Previous industrial pressing of GR may have caused the de-structuration of rhizomes and therefore may have improved EO availability.

Table V -

 V 1. Volatile compounds and antioxidants extracted from ginger plant material. The results are presented in Table V-1. It can be noticed that generally, MHG treatment

	V.3.1.3 Impact of microwave pretreatment on phenolics extraction efficiency
		Constituent water recovered after MHG was analyzed by HPLC to determine its
	content in gingerols (6-gingerol, 8-gingerol and 10-gingerol) and 6-shogaol. Those
	compounds are specific phenolics of ginger, 6-shogaol being a degradation product of 6-
	gingerol by dehydration [76]. They were not detected in the constituent water so we admitted
	that all phenolics remained into GPMHG. GPMHG obtained after MHG process at different
	powers and initial GP were characterized as described in section II.4.1.2.2 in order to show a
	potential effect of MHG treatment on phenolics content, particularly a potential degradation
	of these compounds. A characteristic HPLC chromatogram of extracts is illustrated in Figure
	V-3.
				GR	GP	GPMHG 0.6 W/g 0.8 W/g 1.0 W/g 1.2 W/g 1.4 W/g 1.6 W/g 1.8 W/g
		Yield (g/100g fresh plant material)	0.2	0.3	0.2	0.2	0.2	0.2	0.2	0.2	0.2
			α-pinene	1.2	1.0	2.3	2.6	2.4	2.6	2.3	2.4	2.2
			camphene	4.3	3.8	9.1	10.3	9.2	10.0	9.1	9.4	9.1
			sabinene	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1
			sulcatone	0.0	0.8	1.2	2.8	3.3	3.2	3.0	3.2	2.9
			myrcene	0.6	0.6	0.0	1.4	1.4	1.4	1.3	1.3	1.1
			α-phellandrene	0.2	0.1	0.2	0.3	0.3	0.3	0.3	0.3	0.1
			limonene	0.9	0.9	1.7	1.9	1.9	1.9	1.7	1.8	1.7
			β-phellandrene	4.6	4.2	8.7	10.4	10.3	10.2	9.7	10.0	8.6
	Essential oil	(%) compounds Major	terpinolene linalol borneol α-terpineol citronellol neral geraniol	0.1 0.2 0.5 0.2 0.1 1.7 0.1	0.1 0.2 0.6 0.3 0.3 0.5 0.2	0.1 0.3 0.8 0.4 0.2 0.4 0.1	0.1 0.4 0.9 0.5 0.5 1.3 0.3	0.3 0.4 1.0 0.5 0.4 1.5 0.3	0.3 0.4 0.9 0.5 0.3 1.7 0.2	0.3 0.4 1.0 0.5 0.4 1.5 0.2	0.3 0.4 1.0 0.5 0.4 1.5 0.2	0.2 0.4 1.1 0.6 0.8 1.3 0.6
			geranial	3.3	1.0	0.6	1.9	2.2	2.6	2.3	2.5	2.3
			geranyl acetate	0.3	0.1	0.4	0.2	0.2	0.2	0.2	0.2	0.2
			α-curcumene	3.5	13.9	17.0	7.6	7.2	6.6	7.0	6.8	9.9
			germacrene D	1.6	1.3	0.1	1.3	1.4	1.4	1.4	1.4	0.7
			zingiberene	35.7	25.2	18.4	23.2	24.0	24.0	25.1	24.3	18.4
			α-farnesene	6.5	6.5	6.3	5.4	5.5	5.5	5.7	5.5	5.7
			β-bisabolene	5.7	6.8	0.0	4.8	4.7	4.6	4.8	4.7	5.4
			β-sesquiphellandrene	12.1	13.9	12.3	9.9	9.9	9.7	10.2	9.8	10.4
	Antioxidants	Total content (g/100 g plant material DW) 1.17 Major compounds (g/100 g plant 6-gingerol 0.77 DW) 8-gingerol 0.15 10-gingerol 0.23 material 6-shogaol 0.02	0.90 0.58 0.11 0.19 0.02	0.57 0.31 0.07 0.11 0.08	1.24 0.81 0.14 0.18 0.11	1.06 0.65 0.11 0.19 0.10	1.18 0.79 0.14 0.19 0.08	1.22 0.81 0.14 0.19 0.09	1.37 0.92 0.17 0.21 0.08	1.18 0.79 0.14 0.19 0.08

  Table V-1. This value was determined as 1.37 % of GPMHG. It appeared difficult to extract completely this amount of compounds in water since it exceeds the solubility limit,

		0.60%
		0.50%
	(g/100g)	0.40%
	yield	0.30%
	Global	0.20%
		0.10%
		0.00%
		0	10	20	30	40	50	60	70	80	90	100
						Extraction time (min)
	however it was possible to reach almost 80 % recovery. As shown in Figure V-5, 0.36 % over
	1.37 % gingerols and 6-shogaol were recovered from GPMHG by UAE (16.7 W/cm 2 ;
	0.303 W/cm 3 ), that is only 26 % of available phenolics in GPMHG. From those results, it can
	be concluded that UAE can increase mass extraction yield, which could be due to a
	degradation and solubilization of macromolecules such as fibers. However, US did not appear

  experiment as it was done at laboratory scale. Several food by-products (garlic, onion and GP) were tested in addition to ginger by-products to validate the method. In all cases, a condensate rich in compounds of interest was recovered, what indicates that MHG process can be considered at pilot scale. For industrial scale, MHG equipment has to be designed totally since no equipment is available for now. However, as a follow-up to that study, an industrial up-scaling is currently studied to use MW technology for by-products valorization. For UAE, a 30 L extraction tank from REUS company can be used to up-scale laboratory experiments (FigureII-8 (b)). The reactor is composed of a quadruple output of US at 25 kHz and a power of 4 x 200 W. Up-scaling using this equipment has already been studied in previous studies and showed that UAE is a promising technique that can be considered at industrial scale, especially when water is chosen as solvent[START_REF] Meullemiestre | Impact of ultrasound on solid-liquid extraction of phenolic compounds from maritime pine sawdust waste. Kinetics, optimization and large scale experiments[END_REF].

	the end of
	Extraction plant yield (g extract/100g	material DW)	0 5 10 15 20 25 30	8.6	0.28	9.9	0.31	11.2	0.31	14.7	0.35	19.4	0.36	0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45	Content in gingerols and 6-shogaol in plant material (g/100g DW)
					). MAC-75 apparatus is a multimode MW reactor which contains
	4 magnetrons (4 x 1500 W, 2450 MHz) with a maximum power of 6 kW. Contrary to
	laboratory scale equipment (EOS-GR Microwave Gravity Station), MAC 75 equipment
	contains a removable and rotating PTFE drum where plant material can be loaded. The
	rotation ensures a homogeneous MW distribution to the material treated. The aim of this part
	was to check whether larger scale experiments could be possible for our study. It is not really

an "up-scaling" since the volume of plant material which can be treated and the MW power were at most 75 L and 6 kW respectively. Approximately 4 kg of press cake were therefore submitted to MW during 25 min and condensate (EO and constituent water) was recovered at

  Thus, for "Product recovery", the center corresponds to a recovery of 100 %. Concerning "Energy" and "Process", the maximal values reported on the axis correspond to the values obtained with the CBR.Compared to HD and ethanolic extraction, MHG and UAE enabled to reduce extraction time from 540 min to 110 min. Moreover, in the DBR, no waste was generated as illustrated in Figure II-6, contrary to CBR for which water from HD was considered as waste as it was thrown at the end of extraction. Energy consumption was reduced as well, especially with the replacement of HD by MHG (8.5 kWh and 13.5 kWh for DBR and CBR respectively). Another positive effect of DBR compared to CBR is the absence of organic solvent in the process since none solvent needed to be use for MHG and only constituent water recovered after MHG was employed for UAE. However, DBR was not as efficient as CBR in terms of extraction yields, since a reduction of 55 % for final products recovered was observed for DBR compared to CBR (reduction by 74 % for antioxidants and by 33 % for EO). Yet, DBR was designed to valorize totally ginger by-products with successive and dependent steps whereas in CBR, EO and phenolics were recovered separately and independently by HD and ethanolic extraction respectively. These processes correspond to the processes of reference to recover these compounds that's why better yields were obtained compared to DBR. Finally, the reduced cost of extraction is clearly advantageous for the proposed DBR method in terms of time and energy.This study aims at total valorization of ginger by-products moving towards developing an original concept of DBR. EO was recovered from GP by MHG without solvent and extraction of antioxidants from GPMHG was carried out by UAE using constituent water of GP obtained after MHG as extraction solvent (FigureV-7). Larger scale experiments enabled to show that MHG and UAE are promising techniques which can be considered at pilot scale.Although the effect of US was not significant for extraction of gingerols and 6-shogaol from GPMHG compared with a CM, US considerably improve the mass extraction yield, as a rise of 126 % was noticed between CM and UAE (16.7 W/cm 2 ; 0.303 W/cm 3 ). The DBR also appeared as a greener and cleaner process in contrast with a CBR since extraction time, energy consumption, quantity of organic solvent and waste were decreased. Despite that extraction performance was reduced (decrease of extraction yields by 33 % for EO and by

	V.4 CONCLUSION

Remerciements

ASSESSMENT OF THE BEST SOLVENT FOR THE EXTRACTION OF ROSMARINIC AND CARNOSIC ACIDS FROM ROSEMARY

M. Jacotet-Navarro, M. Laguerre, N. Feuillère, A.-S. Fabiano-Tixier, M. Tenon, A. Bily, F.Chemat, What is the best ethanol-water ratio for the extraction of antioxidants from rosemary? Impact of the solvent on yield, composition and activity of the extracts.

(Submitted)

CONTEXT

Rosemary extracts are widely used in current food processing industry. Lipophilic extracts are obtained with acetone or ethanol whereas hydrophilic extracts are obtained with ethanol or water. At industrial level, both extracts are generally standardized regarding their content in active compounds, but rarely regarding their activity. In this context, it would be interesting to assess the effect of solvent (and more particularly the effect of ethanol ratio in the solvent since it is safer than acetone) on extracts composition but also on extract activity.

ABSTRACT

Extracts rich in antioxidants, such as rosemary extracts, are currently obtained by extraction of the plant material using hydro-alcoholic mixtures with high ethanol content. As this ratio is generally chosen by default and scarcely optimized, we intended to investigate the impact of the hydro-alcoholic composition on extract characteristics such as extraction yield, composition profile in selected compounds, and antioxidant/reducing activity such as Folin-Ciocalteu, DPPH, and ORAC. A theoretical determination of rosmarinic (RA) and carnosic (CA) acid solubilities in ethanol:water mixtures was also performed using COSMO-RS and was confronted to experiments. While the best solubilizing solvent (100% ethanol) was also the best extracting solvent for CA, it was not the case with RA since pure ethanol appeared as a poor solvent compared to 30% ethanol which was optimal. Finally, the best antioxidant activities were obtained with 30% ethanol.

V.2 MATERIALS AND METHODS

A bio-refinery concept was developed for total valorization of ginger by-products. The aim of this DBR was recovering at the end of each consecutive step several high valued compounds, without addition of any external solvent or water. The DBR pattern is illustrated in Figure II-6. As described in the flow sheet, after pressing, GP was firstly submitted to MHG, followed by UAE. To characterize ginger by-products and to assess the performance of DBR, conventional processes (HD and maceration) were performed as reference (Figure Experimental conditions used for each process are described in CHAPTER II. work that the extraction of compounds of interest from rosemary could be intensified using microwaves or ultrasound, and that an extraction selectivity could be achieved according to the technology used; that the two main antioxidants of rosemary could be recovered in a single process using hydro-alcoholic mixtures rather than more harmful solvents such as acetone; and finally that food by-products could be valorized into high value products using a process inspired rom the biorefinery, without solvent nor added water.

LIST OF FIGURES AND TABLES

List of tables

Keywords: green extraction, intensification, solvent substitution, by-products valorization, antioxidant.