Utilisation du jus de datte comme milieu d’immersion pour la déshydratation osmotique des graines de grenade

Poster (2010, October 14)

New insights into the transformation of carbohydrates into platform chemicals

Poster (2010, October 14)

The synthesis of furanic compounds from carbohydrates has become exciting in chemistry and in catalysis studies, because it represents one of the major routes for achieving sustainable energy supply and ... [more ▼]

The synthesis of furanic compounds from carbohydrates has become exciting in chemistry and in catalysis studies, because it represents one of the major routes for achieving sustainable energy supply and chemicals production.1 In particular, 5-hydroxymethylfurfural (5-HMF) and 2-furfural (2-F) occupy a pivotal place and are recognised as versatile and multi-functional starting points for the synthesis of a panel of precursors. Microwaves have readily appeared as a powerfull technique for accelerating reaction rates and increasing selectivities in the field of carbohydrate chemistry.3 In particular, their involvment in combination with heterogeneous catalysts have opened new vistas in the production of bio-oxygenated platform chemicals. The state of the art and main outlook of this strategy are reported here. [less ▲]

Towards the synthesis of mannose derivatives of natural phenolic compounds

Poster (2010, October 14)

The aim of this project is to graft a sugar moiety onto polyfunctional natural phenolic compounds. This should enhance their water solubility. The choice of an adequate sugar such as mannose could provide ... [more ▼]

The aim of this project is to graft a sugar moiety onto polyfunctional natural phenolic compounds. This should enhance their water solubility. The choice of an adequate sugar such as mannose could provide cellular recognition. The synthesis route was first tested on cinnamyl alcohol which is structurally close to the base pattern of natural phenolic compounds. Two compounds are tested to catalyse the glycosilation between cinnamyl alcohol and D-mannose. The first one is an enzyme, the -glucosidase from almond, and the second one is a mineral acid catalyst immobilized on silica. Results show that -glucosidase is able to synthetize cinnamyl mannoside from mannose and cinnamyl alcohol. Furthermore, enzyme-catalyzed route lead to only one product and is so more specific than the chemical route where several products are observed. The obtaining of one product with a unique structure is interesting for the fundamental study of structure-function relationships (Interaction of the product with model membranes by Isothermal Titration Calorymetry and with the Langmuir Trough technique). In a future work, the reaction will be tested with more complex molecules (for example coniferyl alcohol). [less ▲]

A method for the production of prebiotic preparations containing isomaltooligosaccharides and gluconic acid.

Poster (2010, October 14)

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. IMOs consists of glucose ... [more ▼]

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. IMOs consists of glucose monomers linked by at least one α-1-6, or in a lower proportion α -1-3 (nigerose family) or α -1-2 (kojibiose family) glucosidic linkages. In our case they are produced from either corn, tapioca, or rice hydrolyzed starch. The enzymatic reaction is achieved using an Aspergillus niger transglucosidase (EC 2.4.1.24). It results in a very complex mixture with molecules characterized at the same time by their DP value (from 2 to ~15), linkages types (α-1-2, 3 or 6) and the proportion and position of each type of linkage (only α -1-6 or combined types). However, the reaction only permits to reach yields between 50-75 % in IMOs. Impurities are composed of residual maltooligosaccharides (glucose with exclusively α -1-4 linkages) from the starting vegetal material and glucose released during the transglucosylation step. These digestible saccharides are deleterious for the prebiotic preparation. Therefore, these compounds must be eliminated from the medium or converted in prebiotic species. Residual maltooligosaccharides are thus specifically hydrolyzed by a thermostable α-glucosidase (EC. 3.2.1.20) in order to produce glucose as the only unwanted specie. This glucose can then be converted to gluconic acid and/or its salts using a glucose-oxidase (EC. 1.1.3.4) in combination with a catalase. Gluconic acid (C6H12O7) is a saccharide derivative which has been recognized as a prebiotic compound. It is also known for its purgative action and proved to be effective for lipid peroxidation prevention. A first option can then be chosen, leaving gluconic acid in the product in order to obtain an original prebiotic product enjoying new prebiotic potential properties due to the combination of both types of prebiotic compounds (IMO and gluconic acid). The second option is to eliminate the gluconic acid from the prebiotic mixture. This separation doesn’t present the same difficulties than for glucose as gluconic acid is charged and can therefore be separated on anion-exchange resins (Dowex AcO-). This overall process, fulfilling the principles of green chemistry and being applicable to produce organic prebiotic, is an elegant solution, from an economical, an environmental, a nutri-functional and a techno-functional point of view. Indeed, it can lead to original prebiotic preparations, with yields close to 100%, by avoiding product loss, as the digestible saccharides portion is converted to gluconic acid. Furthermore, the presence of gluconic acid can provide many functional properties to the prebiotic preparations for their incorporation in food products. [less ▲]

CARBOHYDRATE-BASED SURFACTANTS FOR FORMING AND STABILIZING COLLOIDAL SYSTEMS AS EMULSIONS AND FOAMS

Poster (2010, October 12)

Binding Interactions of Uronic Acid Derivatives to Lipid Vesicles Investigated By Isothermal Titration Calorimetry

Poster (2010, October 05)

Pretreatment And Enzymatic Hydrolysis Of Miscanthus x giganteus: Influence Of Process Parameters

Poster (2010, September 21)

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and ... [more ▼]

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and hemicellulose content, it has attracted considerable attention as a possible energy crop to produce bioethanol. Pretreatment of lignocellulosic biomass is a key step to unlocking the protective structures so that the enzymatic hydrolysis of the carbohydrate fraction to monosugars can be achieved more easily and with greater yield. In this study, Miscanthus x giganteus was delignified by a chemical pre-treatment process using a mixture of formic acid/acetic acid (1). The treated material was then hydrolyzed. By means of Box-Behnken experimental design and response surface methodology we investigated the effect of cooking time (60, 120 and 180 min), formic acid/acetic acid/water concentration (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107°C) on the residual Klason lignin content and the % of digestibility. The optimal pretreatment process parameters were identified. [less ▲]

Influence of steam explosion and thermal degradation of cellulose

Poster (2010, August 20)

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have ... [more ▼]

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have already been removed by acid and alkaline treatments. The results of this study show that thermal degradation of cellulose fibres, studied by TGA, is still limited for a temperature process below 240 °C. However, derivative TGA show that thermal stability of cellulose obtained by these conditions decreases with the increase of temperature. For temperatures above 250°C, char level is higher at the end of the pyrolysis. According to the literature, the increase of the char level is correlated to an increase of the degradation product1. Determination of the degradation products in the liquor obtained after the pretreatment show an important increase of furfural and 5-hydroxymethylfurfural concentration with the temperature in agreement with the increase of the char level. These results confirm the important degradation of the cellulose fibres. [less ▲]

A Process for the production of a composition, the composition and the use there-of as food additive

Patent (2010)

Influence de l'ajout de co-solvant pour l'estérification du D-mannose et de l'acide D-glucuronique assistée par les lipases

Poster (2010, May)

En parallèle à la production de biocarburant, le second objectif du bioraffinage est la transformation des sucres issus de l’hydrolyse de la lignocellulose en produits d’intérêt, qui se substitueront aux ... [more ▼]

En parallèle à la production de biocarburant, le second objectif du bioraffinage est la transformation des sucres issus de l’hydrolyse de la lignocellulose en produits d’intérêt, qui se substitueront aux produits de la vie courante issus du pétrole. L’une des voies de valorisation envisageable est la synthèse de molécules amphiphiles par greffage de chaînes grasses sur le sucre. Ces composés trouveraient alors des applications dans de très nombreux domaines utilisant les tensioactifs (alimentaire, détergence, peinture,…) . Dans le cadre du programme d’excellence TECHNOSE et du projet d’Action de Recherche Concertées SUPERZYM, deux sucres ont été testés : un polyol, le D-mannose, et un sucre acide, l’acide D-glucuronique. Afin de conférer un caractère amphiphile à la molécule, les lipases ont été utilisées en tant qu’outils d’estérification. Ces triglycérides hydrolases sont en effet capables de catalyser ce type de réaction, et de nombreux exemples dans la littérature démontrent le fort potentiel industriel de ces enzymes , . L’estérification du D-mannose et de l’acide D-glucuronique a donc été mise en œuvre en présence de la lipase de Candida antarctica B (Novozyme 435). La réaction est effective, mais l’ajout de co-solvants tels que la pyridine ou le DMSO améliore les vitesses initiales et les rendements de la réaction. Ces améliorations seront discutées et comparées sur ce poster. [less ▲]