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This study deals with the development of an eco-friendly hydrothermal pretreatment of wheat straw. This pretreatment involves moderate temperatures without generation of liquid fractions allowing to reduce the energy input consumption and the environmental impact and enhance the enzymatic hydrolysis. For this purpose, the synergistic effect of impregnation of wheat straw by dilute sulfuric acid and DIC (in french: Detente instantannee Controlee) pretreatment on enzymatic hydrolysis has been investigated. DIC process involves subjecting the lignocellulosic biomass to saturated steam pressure (0.3–0.7 MPa), followed by a sudden decompression toward vacuum (5 kPa). The optimization of processing conditions was carried out using a full-factorial design, in respect to processing temperature (133–165 °C), residence time (5–40 min) and sulfuric acid concentration (0.70–2.20%). These processing conditions were converted into a single combined severity factor (CS), relating pH, temperature and residence time of pretreatment, ranged from −2.22 to 1.25. The efficiency of proposed pretreatment was measured through the enzymatic digestibility of lignocellulose and the responses parameters of experimental design were the monomeric glucose and xylose. The most influential factor on biomass bioconversion was sulfuric acid concentration followed by temperature and processing time. The optimum values were 2.2%, 165 °C and 40 min, for acid concentration, temperature and residence time, respectively. Strong correlations were observed between the enzymatic hydrolysis and conditions of pretreatment through the analysis of CS. The intense conditions have contributed to disrupt the biomass structure make it less dense leading to a higher specific surface area (A BET ). Thus, increasing in accessibility of cellulose to enzymes has improved the rate and yields of bioconversion.

International audience; Solvent Free Microwave Extraction (SFME) of oil from maritime pine wood waste and its antioxidant activity were investigated and compared to classical hydrodistillation (HD) method (Clevenger apparatus). A central composite design combined with response surface methodology was applied to evaluate the simultaneous influences of irradiation power, irradiation time and moisture content before SFME. A maximal extraction yield of 0.43% (g/100 g dry wood waste) was achieved under optimal extraction time of 43 min and an irradiation power of 668 W compared 0.28% obtained for the conventional method (HD). The results also showed that the three independent variables had a statistical significant effect on the considered response as well their quadratic effects. Gas chromatography coupled to mass spectrometry (GC-MS) analysis showed that SFME extract is richer in oxygenated compounds (~58.5%) compared to HD extract (34.1%). The comparison of total phenolic compounds (TPC) showed that under optimized condition of SFME procedure, the amount of TPC was 74.6 mg GAE/g extract, largely higher than that obtained for HD extraction (51.2 mg GAE/g extract) suggesting that SFME represents an interesting alternative technology for production of recoverable oil from waste issued from maritime pine wood waste. Moreover, the antioxidant activity assessed by 2,2-diphenyl-1-picrylhdrazyl (DPPH) test showed that the concentration that inhibit 50 of DPPH radical was lower for SFME (15.4 µg/ml) compared to HD (123 µg/ml and to a synthetic antioxidant (BHT) (24µg/ml).

International audience; Le séchage par air chaud est souvent accompagné par une altération des qualités fonctionnelles du produit fini. C'est lors de la dernière phase de séchage, lorsque toute l'eau libre a été évacuée, que la qualité est détériorée. Ceci est valable pour un substrat alimentaire mais aussi pour un produit très riche en eau tel que le gel cellulosique qui a fait l'objet de cette étude. Afin de préserver les qualités fonctionnelles, voire les améliorer, nous avons couplé au séchage classique par air chaud un traitement hydro-thermomécanique de très courte durée. La méthode consiste à insérer dans un processus de séchage convectif un traitement hydro-thermo-mécanique. Le gel cellulosique est séché partiellement à l'air chaud jusqu'à une teneur en eau fixée, viens ensuite une étape de traitement hydrothermique à la vapeur d'eau sous pression, pendant une durée fixée, suivi d'une détente rapide vers le vide. Lors de la détente une partie de l'eau contenue dans le produit s'évapore et les contraintes mécaniques engendrées provoquent une texturation de la matière et l'apparition des micro-cavités rendant la structure poreuse. Cette micro-expansion aura pour conséquence, d'une part l'accélération de la cinétique de séchage à l'air chaud lors de la phase finale, et d'autre part de figer la structure pour une meilleure réhydratation ultérieure.

International audience; Les écorces de citrus représentent le principal sous-produit de l'industrie des jus de fruits d'une part et de l'industrie liée à l'extraction des huiles essentielles de citrus d'autre part. Lors d'une étude sur l'extraction d'huile essentielle à partir de peaux d'oranges par un procédé développé au laboratoire (extraction par détente Instantanée contrôlée DIC), les écorces ont été récupérées afin d'évaluer l'impact du procédé sur la disponibilité de la pectine. Le traitement thermomécanique consiste à soumettre les écorces à une pression de vapeur d'eau pendant un temps déterminé. Intervient ensuite une détente instantanée vers le vide (~50 mbar). Cette détente met le système en déséquilibre thermodynamique. Il s'ensuit la création de microcavités dues à une évaporation rapide de l'eau contenue dans les écorces. Après séchage des écorces, ces microcavités vont faciliter la diffusion du réactif utilisé lors de l'hydrolyse acide. Ainsi, le rendement en pectine a été systématiquement supérieur pour des échantillons qui ont subit le traitement thermomécanique en comparaison avec des échantillons témoins, n'ayant subi aucun traitement ; de 20 à 22 % par rapport à la masse d'écorces pour les échantillons traités alors qu'il n'a pas dépassé 12 % pour les échantillons non traités. Trois paramètres ont été simultanément étudiés dans cette étude : le niveau de pression de vapeur d'eau lors du traitement thermomécanique DIC (de 100 à 700 kPa), le temps de séjour à cette pression (0,32 – 3,7 min) ainsi que l'humidité initiale des peaux d'oranges (0,1-0,6 g H2O/ g M.S.). Un plan d'expériences a permis d'évaluer l'effet de ces paramètres sur le rendement en pectine après 6 minutes d'hydrolyse acide. Il est clairement apparu que la pression est le paramètre le plus significatif. Un effet quadratique a également été observé pour ce paramètre, indiquant une dégradation de la pectine à partir d'une certaine température

Une scierie de taille moyenne en France récupère environ 30 m3 de sciure/jour. Le stockage de telles quantités présente un problème écologique à résoudre, surtout que la filière «bois» doit renforcer cette tendance et mener à des quantités sans cesse croissantes de ce sous-produit. La valorisation énergétique de ces déchets est le seul moyen valable pour remédier à ce problème écologique mais son coût d'investissement élevé et ses rendements énergétiques limités freinent sa généralisation. L'extraction des molécules volatiles présentes dans le bois est également intéressante en raison des diverses applications possibles de ses ((huiles essentielles » dans diverses industries. Les procédés utilisés jusqu'à présent permettent d'aboutir à un extrait de faible qualité et à des déchets solides non recyclables. Une co-valorisation de ces deux composantes ; molécules volatiles et déchets solides semble cependant séduisante. Le procédé que nous proposons (Détente Instantanée Contrôlée D.l.C) tente de répondre à ces deux objectifs. Il s'agit d'un procédé de type HTST (Hot Temperature Short Time) basé sur un court séjour de la matière sous une pression de vapeur de 6 bar suivi par une détente instantanée vers le vide. Ce processus permet non seulement l'évaporation des molécules mais aussi leur refroidissement rapide. L'analyse GC/MS des extraits du cèdre rouge (Western Red Cedar) produit par le procédé D.I.C montre l'absence de toute dégradation thermique. Ceci peut être expliqué par un temps de traitement très court (de l'ordre de quelques minutes au lieu de quelques heures pour les procédés classiques). Le rendement d'extraction est de l'ordre de 1.2 % alors qu'il n'est que de 0.8 % pour l'entraînement à la vapeur. Dans le but d'évaluer l'effet de ce traitement sur la surface spécifique du bois, nous avons procédé à une activation chimique au 1-13P04 suivi d'une pyrolyse à 700°C sous azote pendant 1 heure. Cette activation aboutit à un charbon actif possédant des diamètres de pores supérieurs à 20 Â et des surfaces spécifiques relativement élevées avec une isotherme d'adsorption de types IV comportant une hystérésis de type H4 où le nombre de couches de molécules adsorbées n'est pas limité

International audience; Experiments to extract the essential oil from maritime pine (pinus pinaster) were carried out using the instantaneous controlled pressure drop process: "Détente Instantanée Contrôlée" (D.I.C). This process involves subjecting the maritime pine needles for a short period of time to a steam pressure varying from 2 to 5 bar (120 to 150 °C) during a fixed processing time, followed by an instantaneous decompression towards a vacuum (about 50 mbar). In this contribution, we have studied the effect of processing pressure and processing time of pinus pinaster needles on the extraction yield and on the composition of the extracted oil. A detailed attention was attached two three important qualitative molecules namely: alpha-pinène, beta-pinène and germacrene D. The processing pressure was varied from 2 to 5 bar and the processing time from 1 to 35 minutes. The variation of processing pressure from 2 to 5 bar was carried out at 4 minutes processing time. The extraction yield varied respectively from 0.38 to 2.02 g/100 g dry material. However, the optimum can be considered between 3 and 4 bar due to a certain degradation of alpha-pinene indicated by a diminution of the percentage of this molecule in the extracted oil when the processing pressure exceeds 4 bar. The effect of processing time was studied from 1 to 35 minutes at optimised processing pressure of 4 bar. At this processing pressure, the optimum essential oil extraction yield of 2 g/100 g dry material basis was obtained at 8 minutes processing time. For the three studied molecules, two behaviours were observed: for the less volatile one (alpha-pinene), 1 minute of processing time is sufficient to extract the totality of this compound present in the raw material. Increasing of processing time leads to a decrease of the yield of alpha-pinene. For the two others molecules (beta-pinene and germacrene D), increasing of processing time from 1 to 35 minutes induced an increase of their percentages in the extracted oil from 16.4 and 1.37 to 27.3 and 2.61 respectively

International audience; Response surface methodology (RSM) was used to evaluate the effects of processing parameters of a recent extraction process: the instantaneous controlled pressure drop (D.I.C, “Détente Instantanée Contrôlée”) on the extraction yield of maritime pine oil (Pinus Pinaster). This process involves subjecting the pinus pinaster needles for a short period of time to a steam absolute pressure varying from 1.5 to 5.5 bar and then dropping the pressure instantaneously towards a vacuum at 50 m bar. In this study, the tested parameters were the processing steam pressure (defining the processing temperature) and the processing time (between 4 and 20 minutes) and the responses were the global extraction yield and the extraction yield of three important qualitative molecules namely: a-pinène, b-pinène and germacrene D. The optimum processing conditions selected for the global extraction yield of essential oil obtained from response surface analysis were as follows: pressure level: 5.5 bar; processing time: 20 min. Under these conditions, the experimental extraction yield of essential oil (1.92 %) was close to the predicted values calculated from the polynomial response surface model equation. For the three studied molecules, two behaviours were observed: for the less volatile one (a-pinene), 1 minute of processing time is sufficient to extract the totality of this compound present in the raw material. Increasing of processing time leads to a decrease of the yield of a-pinene. For the two others molecules (b-pinene and germacrene D), increasing of processing time from 4 up to 20 minutes induced an increase of their percentages in the extracted oil from 16.4 and 1.37 to 27.3 and 2.61 respectively. The classification of the effects of processing parameters indicates that both processing pressure and processing time have a significant effect on the yields of these molecules. However, a quadratic effect of processing time was observed for a-pinene, indicating a certain degradation of this molecule when the processing pressure exceeds 12 minutes. In a lesser extent, the same quadratic effect was observed for processing pressure. The selection of the optimal extraction conditions must take into account these limits and to be not only governed by an augmentation of global extraction yield. It should be also noted that the yield obtained at industrial scale, by steam distillation is about 0.8 % (d.b) for 6 hours of steam distillation. The same percentage was obtained at after 12 minutes processing time (at 3.5 bar) with the developed extraction process.

Le fil conducteur des travaux de recherches qui font l'objet de ce mémoire est le matériau « bois ». En effet, après des travaux de thèse liés à sa valorisation énergétique, mes recherches ce sont orientés sur la valorisation chimique de la biomasse en cherchant à extraire des substances extractibles à haute valeur ajoutée par une technique différentes de celles généralement adoptées que sont l'entraînement à la vapeur d'eau ou l'extraction au travers de solvants organiques. La technique développée est la détente instantanée contrôlée (DIC). Celle-ci permet de réduire la durée et la consommation énergétique et de s'affranchir, le plus souvent des étapes initiales de broyage et de séchage. La dernière partie traite de la mise au point d'un procédé de restauration et de préservation de bois archéologiques gorgés d'eau par une imprégnation à l'amidon suivie d'un traitement thermique puis un séchage. En effet, La problématique de la restauration - conservation des objets en bois gorgés d'eau est à la fois ambitieuse et délicate. La prise en compte de la qualité esthétique des objets, couplée à la stabilisation de forme et de dimension sont d'une exigence primordiale pour caractériser la réussite de tout procédé de traitement de conservation.

International audience; We performed experiments using starch and its derivatives for impregnation coupled with thermal treatment and a new drying process called the Successive Pressure Drops Dehydration (DDS). This treatment aims to stabilise the archaeological waterlogged woods originated from different museums in France, Italy and Spain. Over all anti-shrink efficiency, (ASE) values in range of 77 to 94% were achieved. We chose to use the corresponding normal measured shrinks which values lay between 4,19 and 8,8 %. The resulting appearance, based on the colour analysis and the splits checking of the treated samples, was aesthetically pleasing. The scanning electronic microscopy and the determination of the dry matter gain showed that the starch and its derivatives penetrated and partially bulked the degraded woods. The experimental results showed that the devised process, starch impregnation plus thermal treatment and DDS, was a suitable treatment method for the conservation of the waterlogged wooden artefacts.

National audience

International audience; Wheat straw was pretreated with a thermomechanical process developed in our laboratory to increase the enzymatic hydrolysis extent of potentially fermentable sugars. This process involves subjecting the lignocellulosic biomass for a short time to saturated steam pressure, followed by an instantaneous decompression to vacuum at 50 mbar. Increasing of the heat induced by the saturated steam result in intensive vapour formation in the capillary porous structure of the plant material and the subsequent release of the pressure to vacuum allows fixing the structure. The process parameters tested in this study were the processing pressure between 3 and 7 bar and the particle size of crushed wheat straw. Enzymatic hydrolysis was performed on the pretreated solids by celluclast (1.5L). The results showed that the hydrolysis yield of wheat straw treated at pressure levels of 3, 5 and 7 bar for a processing time of 15 min was strongly improved compared to hydrolysis yield of un-pretreated wheat straw.

International audience; Essential oil from pine maritime needles is generally extracted by steam distillation process at atmospheric pressure for more than one hour, or by solvent extraction process. In the last decade, there has been an increasing demand for new extraction techniques enabling automation, shorter extraction time and reduced consumption of organic solvent. In this study, Response Surface Methodology (RSM) was used to evaluate the effects of two processing parameters of an alternative extraction process: instantaneous controlled pressure drop: "Détente Instantanée Contrôlée" (D.I.C) on the yield and composition of oil isolated from maritime pine needles (Pinus pinaster). This process involves subjecting the substrate for a short time to steam varying from 1.5 to 5.5 bar (113 to 155 °C) for 4 to 20 minutes, followed by an instantaneous decompression to a vacuum (about 50 mbar). We studied the effect of processing pressure and processing time on the yield of oil and in three important compounds: -pinene, -pinene and germacrene D. Both the processing pressure and time had a significant effect on all responses studied. For the less volatile compound, -pinene, the maximum quantity was obtained at the lower processing pressure and time, while an inverse trend was observed for -pinene and germacrene D. The models displayed by the experimental design gave R2 higher than 0.92.

International audience; Brewers' spent grain (BSG), the main low-value solid residue, is the major by-product of the brewing industry, representing around 85 % of the total by-product generated. This raw material is renewable, at low cost, largely available throughout the year and produced in large quantities. BSG was hydrothermally treated by instantaneous controlled pressure drop process (DIC) at five pressure levels (or five temperatures), with as objective to observe the effect of the processing pressure on enzymatic hydrolysis of BSG. Enzymatic hydrolysis was performed on the pretreated solids by celluclast (1.5L). The results showed that the hydrolysis yield of BSG treated at pressure levels of 2, 3, 4, 5 and 7 bar for a processing time of 15 min was strongly improved compared to hydrolysis yield of unpretreated BSG. The best hydrolysis yield was obtained, up to 100%, when the BSG was pretreated at more intensive conditions (5 and 7 bar for 15 min). The morphology of treated BSG samples was studied with scanning electronic microscopy (SEM). Untreated BSG exhibited rigid and highly ordered fibrils whereas the structure of pretreated BSG at 7 bar seems to have an important disruption.

International audience; Essential oils of thyme (Thymus numidicus (Poiret)) from Algeria were isolated by steam distillation, analysed by gas chromatography coupled with the mass spectrometry (GC-MS) and investigated for their insecticidal activities against Rhizopertha dominica. Contact toxicity of global oil recovered after one hour of extraction and its fraction F1 recovered after 2.5 minutes of extraction were tested using the filter paper method. Analysis of the essential oil made it possible to identify 14 components, representing 75.4 % of the oil. The major components were thymol (51.0 %) followed by carvacrol (9.4 %), linalool (3.3 %), thymol-methyl-ether (3.2 %) and iso-caryophyllene (2.7 %). The evolution of the yield and the composition of essential oil as function of time extraction show that steam distillation is a very rapid process and the duration of extraction could be limited to15 minutes, since more than 94 % of oil are extracted. The toxicity tests show that thyme oil and its fraction F1 have an insecticidal activity, nevertheless, the mortality obtained for global oil are weaker compared with those obtained for the F1 fraction. This toxicity would be allotted to the presence instrong proportion of linalool and thymol.

International audience; The instantaneous controlled pressure drop process (or D.I.C process: “Détente Instantanée Contrôlée”) was used as pre-treatment prior to pectin acid extraction from orange peel. This process involves subjecting the orange peel for a short time to steam pressure varying from 100 to 700 kPa, followed by an instantaneous decompression to vacuum at 5 kPa. Effects of processing pressure, moisture content of peels before the thermomechanical treatment and processing time were examined with response surface methodology. The optimal conditions were determined and the responses surfaces were plotted from the mathematical models. The Fisher test and p-value indicated that both processing pressure and the moisture content of peels before the pre-treatment had highly significant effect on the pectin yield. The quadratic effect of processing pressure as well as the interaction effects of the initial moisture content and processing time had also a significant effect on the response. Moreover, the kinetics of pectin extraction showed that after few minutes of hydrolysis, the yields of pectin were systematically higher than that of control sample and this is important from industrial point of view because the hydrolysis of pectin is generally performed in 10-15 minutes.

International audience

International audience; Solvent Free Microwave Extraction (SFME) of oil from French maritime pine bark waste and its antioxidant activity were investigated and compared to classical hydrodistillation (HD) method (Clevenger apparatus). A central composite design combined with response surface methodology was applied to evaluate the simultaneous influences of irradiation power and irradiation time. A maximal extraction yield of 3.48% (g/100 g dry bark) was achieved under optimal extraction time of 92.4 min and an irradiation power of 803.5 W compared 2.2% obtained for the conventional method (HD). Gas chromatography coupled to mass spectrometry (GC-MS) analysis showed that SFME extract is richer in oxygenated compounds (~40%) compared to HD extract with 26%. The results also showed that the two independent variables had a statistical significant effect on the considered responses namely oil yield, total phenolic compounds (TPC) and antioxidant activity assessed by 2,2-diphenyl-1-picrylhdrazyl (DPPH). Under optimized conditions, the amount of TPC was 139.15 mg GAE/g extract largely higher than that obtained for HD extraction (14.28 15 mg GAE/g extract) suggesting that SFME represents an interesting alternative technology for production of recoverable oil from waste of French Maritime pine bark. The percentage inhibition was also higher for SFME extraction technique (71.91%) than for HD (56.51%) indicating a higher antioxidant activity.

International audience; Experiments were performed to evaluate a recent extraction process called the instantaneous controlled pressure drop process (briefly: DIC process: “Détente Instantanée Contrôlée”) for extracting some volatile compounds from red cedar wood. This process involves subjecting red cedar chips for a short time (30 s to 5 min) under a steam pressure (1 to 6 bars or from 100 to 165 °C). This first step is followed by a flash decompression toward vacuum (up to 50 mbar). This transition induces a fast evaporation of water and volatile compounds and a cooling effect. The effects of two processing parameters (steam pressure and heating time) on the total extraction yield and on yield of four volatile compounds were evaluated by response surface methodology. The results indicated that the processing pressure is the predominant parameter for global extraction yield of oil (E.O= Extracted Oil) and for yield of the four compounds investigated in this study. The processing time is also a significant parameter but less than processing pressure. Moreover, activated carbon produced from DIC-treated residue revealed larger pore sizes compared to untreated samples.

We carried out experiments concerning the treatment by Instantaneous Controlled Pressure-drop (DIC) in the case of juniper berries (Juniperus Excelsa). We study how DIC is able to extract essential oil by applying an abrupt pressure drop toward vacuum whose rate is ΔP/Δt >5bar s−1, which implies an autovaporization of water and some volatile molecules, leads a cooling effect and modifies the structure. We analyze the effect of both steam pressure (from 1 up to 6 bar) and treatment time (from 10 seconds up to 3 minutes) in term of extraction yield. We proved that the higher the pressure, the higher the extraction yields. A double DIC treatment at 6 bars during 150 seconds, allowed us to extract 95 % of essential oils extracted normally in 12 hours by steam distillation.