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See detailTowards the synthesis of mannose derivatives of natural phenolic compounds
Sainvitu, Pauline ULg; Nott, Katherine ULg; Richard, Gaetan ULg et al

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 ▲]

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See detailA method for the production of prebiotic preparations containing isomaltooligosaccharides and gluconic acid.
Goffin, Dorothée ULg; Blecker, Christophe ULg; Paquot, Michel ULg

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 ▲]

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See detailSynthèse assistée par Micro-ondes de dérivés d'acides uroniques
Laurent, Pascal ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

Poster (2010, October 14)

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of ... [more ▼]

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of chemicals from the biomass, such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks is therefore an area of outmost interest. In this context, uronic acids such as glucuronic acid (GlcA) or galacturonic acid (GalA) derived from widely available raw material such as hemicellulose or pectins represent important biocompatible and bioresorbable starting material. The quest of highly effective, environmentally friendly and straightforward chemical strategies to transform totally O-unprotected uronic acids into high valuable materials remains actually a particularly challenging task. A new strategy enabling the quantitative “one-pot” production of water-soluble monosubstituted D-glucofuranosidurono-6,3-lactones from unprotected D-glucuronic acid (D-GlcA) involving microwaves and an inexpensive siliceous-based promoter will be described. The use of a heterogeneous acid catalytic systems consisting of sulfuric acid impregnated onto silica (H2SO4/SiG60) or onto carbon (H2SO4/C), offers a green alternative to unrecyclable liquid sulfuric acid and permit the developpment of a truly eco-friendly green process, as these supported acids were readily separated from liquid products, without neutralization, by decantation or filtration, thus minimizing energy consumption and wastes. Faced with environmental concerns, this solventless methodology offers attractive features, including short reaction times, high yields and easy set-up and workup. [less ▲]

Detailed reference viewed: 102 (17 ULg)
See detailCARBOHYDRATE-BASED SURFACTANTS FOR FORMING AND STABILIZING COLLOIDAL SYSTEMS AS EMULSIONS AND FOAMS
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Richel, Aurore ULg et al

in Abstracts book of 5th edition of world congress on emulsions (2010, October 12)

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable ... [more ▼]

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product concept possibilities, and may occur in a large structural range with one or more hydrophilic head groups and hydrophobic chains with various linkers/spacers, thanks to numerous reactive functional groups in their basic structure. It is then possible to design a quasi-unlimited number of new compounds by (bio)-synthesis from various raw materials. This structural diversity can generate a wide range of properties, which could be developed in food and non-food applications. Our challenge is now to find out the most suitable molecular structures for the post-development of CBS, mainly for colloidal systems like emulsion, foam, and suspension. A pre-screening of the dynamic and equilibrium interfacial tensions and interfacial rheology properties of various CBS prepared by chemical, enzymatic, or chemo-enzymatic synthesis routes from the derivatives of bio-renewable substrates is carried out. Then, the characterization of emulsifying and foaming properties of pre-selected molecules is performed. These investigations are completed by the characterization of thermal properties of liquid suspensions and powders. Homologous series of two derivative compounds of glucuronic and galacturonic acids with mono- or bicatenar hydrophobic chains and different linkages (linear or cyclic ester, amide) have been chosen as CBS starting compounds. These were full characterized by spectroscopic techniques (RMN, SM, IR). The effect of the hydrophobic chain length and number, polar head group, and the linker on whole properties investigated is easily deduced. [less ▲]

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See detailPretreatment And Enzymatic Hydrolysis Of Miscanthus x giganteus: Influence Of Process Parameters
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

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 ▲]

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See detailInfluence of steam explosion and thermal degradation of cellulose
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

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 ▲]

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See detailSteam explosion pretreatment and thermal degradation of cellulose fibers
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Conference (2010, August 20)

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See detailInfluence de l'ajout de co-solvant pour l'estérification du D-mannose et de l'acide D-glucuronique assistée par les lipases
Richard, Gaetan ULg; Brognaux, Alison ULg; Nott, Katherine ULg et al

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 ▲]

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See detailMicrowave-assisted conversion of carbohydrates. State of the art and outlook.
Richel, Aurore ULg; Laurent, Pascal ULg; Wathelet, Bernard ULg et al

Conference (2010, May)

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast ... [more ▼]

The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks (i.e. lignocellulosic biomass) is nowadays an area of outmost interest. In this context, the implementation of fast, expeditous and cost-effective methodologies for the modification of these naturally occurring compounds is becoming a prerequisite. In this sense, the application of microwaves has gained progressive attention in laboratories for making a range of high-added value sugars derivatives scaffolds. Its advantages are numerous and include enhacement of reaction rates and yields combined to improved regio-, chemo- and anomeric selectivities. Since the first publications of Gedye et Giguere in 1986, the use of microwave has progressively emerged as a popular non conventional heating source in the field of organic synthesis.1 Nevertheless, its application in the area of carbohydrate chemistry is less documented.2, 3 Although research in this field is still in its infancy, recourse to microwaves often provides, with remarkable yields and atom efficiency, new carbohydrate-based structures that are not easily available by any another means (or only via painstaking multi-step protocols). This communication proposes therefore selected, recent and non exhaustive illustrations of the application of microwaves to promote famous carbohydrates “model” reactions. The scale-up of such microwave-assisted reactions is also presented. [less ▲]

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See detailMicrowave – assisted synthesis of carbohydrate compounds, focus on uronic acid derivatives.
Laurent, Pascal ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

Poster (2010, May)

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of ... [more ▼]

At the moment, biorefining is increasingly seen as a promising alternative to petrochemical sector since it targets both the replacement of part of petroleum as a source of energy and the development of chemicals from the biomass, such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates arising from the hydrolysis of renewable feedstocks is therefore an area of outmost interest. In this context, uronic acids such as glucuronic acid (GlcA) or galacturonic acid (GalA) derived from widely available raw material such as hemicellulose or pectins represent important biocompatible and bioresorbable starting material. The quest of highly effective, environmentally friendly and straightforward chemical strategies to transform totally O-unprotected uronic acids into high valuable materials remains actually a particularly challenging task. A new strategy enabling the quantitative “one-pot” production of water-soluble monosubstituted D-glucofuranosidurono-6,3-lactones from unprotected D-glucuronic acid (D-GlcA) involving microwaves and an inexpensive siliceous-based promoter will be described. The use of a heterogeneous acid catalytic systems consisting of sulfuric acid impregnated onto silica (H2SO4/SiG60) or onto carbon (H2SO4/C), offers a green alternative to unrecyclable liquid sulfuric acid and permit the developpment of a truly eco-friendly green process, as these supported acids were readily separated from liquid products, without neutralization, by decantation or filtration, thus minimizing energy consumption and wastes. Faced with environmental concerns, this solventless methodology offers attractive features, including short reaction times, high yields and easy set-up and workup. [less ▲]

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See detailPectin extraction from lemon by-product with acidified date juice : effect of extraction conditions on chemical composition of pectin.
Masmoudi, M.; Besbes, Souhail; Chaabouni, M. et al

in Food Science & Technology International (2010), 16(2), 105-114

The microstructure and the rheological properties of lemon-pectin mixtures were studied and compared to those of pure lemon (high methoxyl: HM) and date (low methoxyl: LM) pectins. Rheological properties ... [more ▼]

The microstructure and the rheological properties of lemon-pectin mixtures were studied and compared to those of pure lemon (high methoxyl: HM) and date (low methoxyl: LM) pectins. Rheological properties were carried out in the presence of 30%, 45% and 60% sucrose, and increasing calcium concentrations (0-0.1%). The presence of date with lemon pectin led to a gel formation at 45% sucrose and in the presence of calcium, which was not the case for lemon pectin alone under the same conditions. It is suggested that lemon and date pectins interacted, leading to gel formations at different gelling temperatures, which were strongly dependant on degree of methylation. These results were confirmed by scanning electron microscopy, which revealed inhomogeneous gels where dense aggregated network and loose, open network areas were present. Addition of calcium to pectin mixture gels led to stronger and faster gel formation. [less ▲]

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See detailLipase-assisted synthesis of potential bio-based surfactants starting from lignocellulosic carbohydrates
Richard, Gaetan ULg; Nott, Katherine ULg; Paquot, Michel ULg et al

Poster (2010, April)

Surfactants constitute an important class of compounds with a lot of applications, especially in the food and beverage industries (emulsion forming and stabilization, antiadhesive and antimicrobial ... [more ▼]

Surfactants constitute an important class of compounds with a lot of applications, especially in the food and beverage industries (emulsion forming and stabilization, antiadhesive and antimicrobial activities)1. With the prospect of synthesising new active compounds, white biotechnology offers efficient tools. Indeed, the use of enzymes as biocatalysts provides an interesting synthetic route in comparison to the chemical way that often requires high reaction temperatures and suffers from a lack of specificity, resulting in complex mixtures. Among all the biocatalysts available, lipases represent a class of industrial interest 2,3. In parallel, the starting material is also an important parameter : due to the depletion of petroleum reserves, its ever increasing price and various environmental aspects, the use of renewable or biomass resources is inevitable. Within the frame of a biorefinery project, we focused on the lipase-assisted modification of uronic acids. These carbohydrates can be obtained from lignocellulosic material, and, in the presence of fatty alcohols, the Candida antarctica lipase B catalyses the synthesis of amphiphilic compounds. Owing to the initial conditions used and the addition of co-solvents, we optimized the synthesis of these bio-based potential surfactants, and obtained a panel of various structures depending to the acyl acceptor used. The poster will present the details of these syntheses. [less ▲]

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See detailImpact of the crystallisation pathway of inulin on its mono-hydrate to hemi-hydrate thermal transition
Ronkart, Sébastien; Deroanne, Claude; Paquot, Michel ULg et al

Poster (2010, March 22)

Inulin plays a major role in the food industry as dietary fibre, bulking agent and fat or sugar substitute. Thermal properties of two inulins obtained from different crystallisation pathways were ... [more ▼]

Inulin plays a major role in the food industry as dietary fibre, bulking agent and fat or sugar substitute. Thermal properties of two inulins obtained from different crystallisation pathways were investigated. The first one, was obtained by fractional precipitation of a saturated inulin solution (40/120). The second one, came from a solid amorphous inulin (95/120). These two inulins were spray dried with an inlet air temperature of 120°C. Then, these powders were placed into controlled atmosphere conditions at 0 % HR during one week and at 94% during the same time. Finally the two inulins were called 40/120/94% and 95/120/94% and their thermal properties were investigated by Wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), temperature resolved wide angle X-ray scattering (TRWAXS) and thermogravimetry (TGA).Although WAXS did not show any difference between the two inulin, thermal analysis revealed the existence of a hemi-hydratate inulin (40/120/94%). This fact has an implication on the processing of the powder at an industrial level. Indeed, 40/120/94% has shown an agglomeration whereas 95/120/94% was a continuous mass. In other words, polymorphism of inulin crystals induces technofunctionality changes of the powder (hygroscopy, solubility, etc.) which could have an impact during processing or formulation of the powder. [less ▲]

Detailed reference viewed: 41 (13 ULg)