References of "Paquot, Michel"
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See detailImpact of the crystallisation pathway of inulin on its mono-hydrate to hemi-hydrate thermal transition
Ronkart, S. N.; Deroanne, C.; Paquot, Michel ULg et al

in Food Chemistry (2010), 119(1), 317-322

In this paper, we present the thermal properties of two inulins obtained from different crystallisation pathways. One was obtained by fractional precipitation of a saturated inulin solution and the second ... [more ▼]

In this paper, we present the thermal properties of two inulins obtained from different crystallisation pathways. One was obtained by fractional precipitation of a saturated inulin solution and the second was from the crystallisation of a solid amorphous mulin. The thermal analyses were conducted by temperature resolved wide angle X-ray scattering (TRWAXS), differential scanning calorimetry (DSC) and thermogravimetry (TG). Although at room temperature both inulins presented similar X-ray diffractogram patterns characteristic of the mono-hydrate polymorph, they differed considerably by their thermal properties. During heating, a difference in the mono-hydrate to the hemi-hydrate polymorph transition occurred. Thermogravimetric analysis suggested a difference in the water mobility inside the material which had an impact on the thermal properties and hydrate transition of the crystalline inulin. (C) 2009 Elsevier Ltd. All rights reserved. [less ▲]

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See detailComparison of the glucooligosaccharide profiles produced from maltose by two different transglucosidases from Aspergillus niger
Goffin, Dorothée ULg; Wathelet, Bernard ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010)

Prebiotic isomaltooligosaccharide preparations contain α-D-glucooligosaccharides and their structure is the key factor for their prebiotic potential. The transglucosylation selectivity is known to depend ... [more ▼]

Prebiotic isomaltooligosaccharide preparations contain α-D-glucooligosaccharides and their structure is the key factor for their prebiotic potential. The transglucosylation selectivity is known to depend on the enzyme specificity and moreover, maltose and -glucooligosaccharides can actually act as both glucosyl donor and acceptor in the reaction. Thus, two commercial enzymes, a glycosyl-tranferase and an -glucosidase, were tested alone and in combination on pure maltose to study their specificities and the IMO profile obtained. The reactions were monitored using a step-forward AEC-PAD analytical method which permitted to detect and resolve new unknown IMO. Structural determination of unknown IMO was attempt using their retention times and relative abundance. As a general rule, the -glucosidase has a more expressed hydrolyzing activity leading to products containing less residual digestible -(1-4) linkages such as isomaltose, isomaltotriose, isomaltotetraose, kojibiose and nigerose while the glucosyl-transferase produces important amount of panose. Finally, the combination of the two enzymes leaded to an intermediate IMO profile. IMO syrups composition was thus proved to be dependant on the specificity of the transglucosylating enzyme so that products profiles can be designed using different enzymes and in different proportion. [less ▲]

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See detailMicrowave-assisted transformations of agroresources: an example of green chemistry
Richel, Aurore ULg; Laurent, Pascal ULg; Paquot, Michel ULg

Report (2010)

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as a promising renewable alternative. Alongside its traditional involvement in the agro-food, the ... [more ▼]

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as a promising renewable alternative. Alongside its traditional involvement in the agro-food, the biomass has nowadays opened new vistas in the non-food sector. Indeed, original products and structures, potentially biodegradable, are proposed as substitutes for conventional petrochemical derivatives. The steady rise of oil prices, on the one hand, and the implementation of a new European legislation (REACH: Registration, Evaluation and Authorization of Chemicals), on the other hand, have only help to boost the academic and industrial research in this area. In this context, microwave-mediated synthesis has progressively emerged as a green chemistry technology. Application of microwaves (MW) as a non conventional heating source finds a plethora of illustrations in the field of organic synthesis. Microwaves usually accelerate chemical processes, while offering improved yields and selectivities. MW heating enables reactions under solventless conditions, providing unique chemical pathways, with special advantages such as ease of manipulation and reduction (or prevention) of pollution "at source". Various reactions and processes can be applied to transform lignocellulosic raw materials into valuable fuels and chemicals. Selected examples of strategical modifications of renewable biomass feedstocks via activation by microwave irradiation are proposed herein. [less ▲]

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See detailDevelopment of gelling properties of inulin by microfluidization
Ronkart, Sebastien N; Paquot, Michel ULg; Deroanne, Claude et al

in Food Hydrocolloids (2010), 24(4), 318-324

In this paper, we report the impact of a microfluidic device (Microfluidizer (R)) on the development of gelling properties of inulin-water systems. Inulin dispersions at a concentration of 2, 7 and 15%, w ... [more ▼]

In this paper, we report the impact of a microfluidic device (Microfluidizer (R)) on the development of gelling properties of inulin-water systems. Inulin dispersions at a concentration of 2, 7 and 15%, w/w, were subjected to microfluidization treatments at 30 MPa with various numbers of circulations in the apparatus (1, 2 or 5 passes). The high shear stress treatment did not induce a chemical composition change of inulin. However, it allowed an increase of the gel-like behavior of the system as well as the viscosity of the inulin dispersion, transforming a visual aspect of the product similar to milk, to a system similar to yogurt or margarine depending on the concentration and the number of passes in the Microfluidizer (R). The viscosity increased with both the number of passes and the inulin concentration. Granulometry as well as optical and electronic microscopy ascertained the reduction of the particle size and the formation of a network composed of agglomerates which interacted with the solution and thus led to textural modifications. (C) 2009 Elsevier Ltd. All rights reserved. [less ▲]

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See detailMicrowave-assisted transformations of carbohydrates
Richel, Aurore ULg; Wathelet, Jean-Paul ULg; Paquot, Michel ULg

in SciTopics / Research Summaries by Experts (2010)

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See detailMicrowave-assisted synthesis of D-glucuronic acid derivatives using cost-effective solid acid catalysts
Richel, Aurore ULg; Laurent, Pascal ULg; Wathelet, Bernard ULg et al

in Tetrahedron Letters (2010), 51

Monomode microwave-assisted coupling of D-glucuronic acid with alcohols, in the presence of various impregnated acid catalysts, was successfully performed, affording in almost quantitative yields the ... [more ▼]

Monomode microwave-assisted coupling of D-glucuronic acid with alcohols, in the presence of various impregnated acid catalysts, was successfully performed, affording in almost quantitative yields the corresponding monosubstituted b-D-glucofuranosidurono-6,3-lactones in less than 10 min at 85°C. This study evidences the synergy of microwaves and impregnated acid catalysts as a fast and clean strategy in the field of carbohydrate chemistry. [less ▲]

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See detailLA STEAM EXPLOSION : PRINCIPE ET ACTION SUR LES MATERIAUX LIGNOCELLULOSIQUES
Jacquet, Nicolas ULg; Blecker, Christophe ULg; Paquot, Michel ULg

Poster (2009, December 16)

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites ... [more ▼]

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites par la formation d’acides organiques et du cisaillement résultant de la chute brutale de pression. Le procédé est composé de deux phases distinctes. D’une part, le vapocraquage qui consiste à faire pénétrer par diffusion, puis à condenser, la vapeur sous haute pression à l’intérieur de la structure du matériau. L’eau condensée à température élevée va initier l’hydrolyse des groupements acétyles contenus dans les xylanes et induire la formation d’acides organiques. Selon la sévérité des conditions (pression, température), les acides vont catalyser l’hydrolyse des fractions hémicellulosiques, induire des modifications dans la structure des lignines et modifier le degré de cristallinité de la fraction cellulosique. D’autre part, la décompression explosive. Cette phase est provoquée par une chute brutale de pression qui va entraîner la revaporisation d’une partie de l’eau condensée. L’expension brutale de la vapeur va induire des forces de cisaillement qui vont modifier les propriétés physiques (granulométrie, surface spécifique, rétention d’eau…) du matériau. [less ▲]

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See detailVapocraquage et Steam Explosion
Jacquet, Nicolas ULg; Paquot, Michel ULg

Conference (2009, October 21)

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See detailSynthèse enzymatique de surfactants sucrés dans le CO2 supercritique
Favrelle, Audrey ULg; Brognaux, Alison ULg; Debuigne, Antoine ULg et al

Poster (2009, October 15)

Les esters de carbohydrates sont des surfactants non ioniques ayant un vaste éventail d’applications commerciales en particulier dans l’industrie cosmétique, alimentaire et pharmaceutique. Ils sont ... [more ▼]

Les esters de carbohydrates sont des surfactants non ioniques ayant un vaste éventail d’applications commerciales en particulier dans l’industrie cosmétique, alimentaire et pharmaceutique. Ils sont produits à partir de matières premières renouvelables et peu coûteuses, et sont biodégradables et non toxiques. De manière générale, la synthèse d’esters de sucre nécessite de nombreuses étapes de protection/déprotection des groupements hydroxyles, le nombre et la position exacte des substituants greffés sur un squelette osidique étant des paramètres difficiles à contrôler lors des réactions chimiques. En revanche, la spécificité de certaines enzymes, et en particulier des lipases, peut être mise à profit pour modifier les sucres en milieux organiques. L’utilisation des lipases permet ainsi un meilleure sélectivité et énantiosélectivité des réactions d’estérification et de transestérification. D’autre part, la voie enzymatique permet d’effectuer ces réactions dans des conditions expérimentales beaucoup plus douces de température, de pH et de pression, par rapport aux synthèses réalisées à l’aide de catalyseurs chimiques. Le dioxyde de carbone supercritique (Sc-CO2), quant à lui, constitue une alternative intéressante aux solvants organiques couramment utilisés dans ce domaine car il est non toxique, chimiquement inerte, non inflammable…. Par exemple, son utilisation réduit la contamination des produits finaux avec des solvants résiduels. Ces avantages lui confèrent un large potentiel d’applications notamment dans l’industrie alimentaire, cosmétique, pharmaceutique mais également des matériaux. Notre travail consiste donc à développer la synthèse enzymatique de surfactants sucrés en milieu Sc-CO2 et d’étudier l’influence de divers paramètres sur la réaction biocatalysée. L’activité enzymatique et les rendements observés lors de nos expériences préliminaires dans le Sc-CO2 seront présentés ici et comparés avec ceux obtenus dans des solvants organiques traditionnels. [less ▲]

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See detailOptimisation de l'acylation enzymatique du mannose par l'utilisation de co-solvants
Brognaux, Alison ULg; Favrelle, Audrey ULg; Deleu, Magali ULg et al

Poster (2009, October 15)

Les esters de sucres sont des surfactants non-ioniques avec de nombreuses applications dans l’industrie alimentaire et pharmaceutique. La synthèse enzymatique est généralement préférée à la synthèse ... [more ▼]

Les esters de sucres sont des surfactants non-ioniques avec de nombreuses applications dans l’industrie alimentaire et pharmaceutique. La synthèse enzymatique est généralement préférée à la synthèse chimique. En effet, cette dernière consomme beaucoup d’énergie, est moins sélective envers les différents groupes hydroxyle du sucre et conduit à des produits de caramélisation. Le type de solvant, le ratio sucre / lipide, la température et le type de lipase immobilisée peuvent être modifiés afin d’optimiser la vitesse initiale et le rendement de réaction. Les travaux décrits rapportent l’optimisation de la synthèse enzymatique de myristate de mannosyle à partir de mannose et d’acide myristique en présence de la lipase de Candida antarctica B (Novozyme 435). Les concentrations optimales en mannose et en acide myristique sont respectivement de 0,1 et 0,6 M dans du tert-butanol pur à 60°C. Ces conditions conduisent à une vitesse initiale de 1,3 g/l.h pour 2 g/l d’enzyme et à un rendement molaire de 55%. Afin d’améliorer cette vitesse initiale de réaction, différents mélanges de tert-butanol et de co-solvants polaires ont été testés. Les solvants polaires (log P faibles) augmentent la solubilité des sucres mais provoquent l’inactivation partielle des lipases. Lorsque le log P est supérieur à 3, l’enzyme reste active mais ce type de milieu n’est pas approprié si les deux substrats diffèrent grandement en terme de polarité. Le but de cette étude est donc de trouver un compromis entre la solubilité du sucre et le maintient de l’activité enzymatique. Les quatre co-solvants testés sont le DMSO, le DMF, le formamide et la pyridine. Au terme de ce travail, le DMSO, à raison de 10 % dans le milieu réactionnel, s’est avéré être le meilleur co-solvant parmi ceux testés. Dans ces conditions, la vitesse initiale de réaction est accrue de 130 %. [less ▲]

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See detailEnzymatic modifications of sugar in supercritical carbon dioxide
Favrelle, Audrey ULg; Brognaux, Alison ULg; Debuigne, Antoine ULg et al

Poster (2009, July 07)

Carbohydrates esters are non-ionic surfactants that have a wide range of commercial applications in cosmetic, food and pharmaceutical industry. They are produced from renewable and inexpensive raw ... [more ▼]

Carbohydrates esters are non-ionic surfactants that have a wide range of commercial applications in cosmetic, food and pharmaceutical industry. They are produced from renewable and inexpensive raw materials, are bio-degradable and non-toxic. Chemical synthesis of sugar esters is generally performed at a high temperature in the presence of an alkaline catalyst lead-ing to a mixture of products. In this respect, the corresponding enzyme-catalyzed processes in non-conventional media are more selective. For this purpose, lipases are the most useful enzymes. Moreover, supercritical carbon dioxide (SC-CO2) constitutes an interesting alternative to the organic solvents used in the domain as it is considered to be environmentally frien-dlier and safer. For example, its use reduces the contamination of the final products with residual solvents. This property is particularly valued in food, cosmetic and pharmaceutical industry. Our work consists to carry out lipase catalyzed sugar modifications in SC-CO2 and to compare the results with those obtained in organic solvents. The effect of these two different media on the enzyme stability and the yield will be described here. Moreover, the impact of various factors such as pressure, temperature, enzyme form (free or immobilized), use of co-solvent, on the course of the sugar esterification will be discussed. [less ▲]

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See detailStudy of thermomyces ianuginosa lipase in the presence of tributyrylglycerol and water
Santini, Sébastien; Crowet, Jean-Marc ULg; Thomas, Annick ULg et al

in Biophysical Journal (2009), 96(12), 4814-4825

The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze ... [more ▼]

The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze both hydrolysis at high water contents and transesterification in quasi-anhydrous conditions. Here, we investigated the Thermomyces lanuginosa lipase structure in solution in the presence of a tributyrin aggregate using 30 ns molecular-dynamics simulations. The water content of the active-site groove was modified between the runs to focus on the protein-water molecule interactions and their implications for protein structure and protein-lipid interactions. The simulations confirmed the high plasticity of the lid fragment and showed that lipid molecules also bind to a secondary pocket beside the lid. Together, these results strongly suggest that the lid plays a role in the anchoring of the protein to the aggregate. The simulations also revealed the existence of a polar channel that connects the active-site groove to the outside solvent. At the inner extremity of this channel, a tyrosine makes hydrogen bonds with residues interacting with the catalytic triad. This system could function as a pipe (polar channel) controlled by a valve (the tyrosine) that could regulate the water content of the active site. [less ▲]

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See detailProduction of Biopolymers from Sugar Beet Pulp
Meyer, Laurence ULg; Paquot, Michel ULg; Dubois, Philippe

Poster (2009, May)

Sugar beet pulp is an important by-product of the sugar industry. In order to make the most of this waste, pectin extraction can constitute an economical solution. Pectin is commonly used in food industry ... [more ▼]

Sugar beet pulp is an important by-product of the sugar industry. In order to make the most of this waste, pectin extraction can constitute an economical solution. Pectin is commonly used in food industry as a gelling agent. However, in the present study another use of pectin is considered: its potential embedding into biodegradable polymer films which can further be used in plastic industry. At first, different pectin extraction methods have been developed on sugar beet pulp in order to obtain four different types of pectins characterized at the same time by their molecular weight degree of esterification. Acidic extraction leads to pectin of high molecular weight and high degree of esterification. From this pectin, a de-esterification and a de-polymerization allow us to obtain, respectively, a pectin of high molecular weight and low degree of esterification and a pectin of low molecular weight and high degree of esterification. On the other hand, a basic extraction leads to pectin of low molecular weight and degree of esterification. Preliminary, tests have been conducted on mixes comprising 5, 10, 15, 20 % of commercial pectin and PLA (polylactic acid) or PBAT (Polybutylen-adipate terephtalate). In all cases, the products were not stable and therefore the use of a compatibilizing agent was required. Glycerol and D-Sorbitol were thus studied for that purpose, in mixing ratios between 40-80 % with commercial pectin. The best mechanical properties (Young modulus; yield stress and yield strain) were obtained with the pectin/sorbitol 50/50 mix. This proportion was then used with our different sugar beet pulp extracted pectins to produce PLA/pectin/Sorbitol 50/25/25 formulations. The best mechanical properties were reached with the low molecular weight end degree of esterification pectin. Indeed, the relative small size of this pectin with the lack of esterified groups enables interactions between pectin chains plastified by sorbitol and PLA. These interactions lead to a better cohesion of the high pectic content biomaterial. [less ▲]

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See detailChemical and enzymatical modifications of sugar derived from lignocellulose
Richard, Gaetan ULg; Laurent, Pascal ULg; Nott, Katherine ULg et al

Poster (2009, January)

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from ... [more ▼]

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from biomass, with applications such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates from renewable raw materials is currently the subject of numerous researches. In this context, the synthesis of new surfactants derived from the sugars issued from the lignocellulose hydrolysis was undertaken by chemical or enzymatic routes. In this poster, the examples of glucose, cellobiose and uronic acids will be discussed. Whatever the way used, the reaction conditions (use of a catalyst, protection/deprotection steps, type of solvent, presence of co-solvent, reactant concentrations, etc) were optimized to yield a panel of carbohydrate derivatives (some examples of the structures obtained are given above). These differ by the nature of the alkyl chain (in length and in degree of saturation), the type of chemical bond (amide, ester, thioester, acetal), and the position of substitution. The impact of these differences on the techno-functional properties of these modified sugars will be evaluated. [less ▲]

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See detailInteresterification of rapeseed oil with anhydrous milk fat and its stearin fraction. II. Modifications of melting properties
Giet, Jean-Michel ULg; Aguedo, Mario ULg; Hanon, Emilien ULg et al

in GCIRC Bulletin (2009), 25

Chemical and/or physical modification of oils and fats are commonly used by food industry to widen their range of applications (1,2). Lipase-catalysed interesterification of anhydrous milk fat (AMF) and ... [more ▼]

Chemical and/or physical modification of oils and fats are commonly used by food industry to widen their range of applications (1,2). Lipase-catalysed interesterification of anhydrous milk fat (AMF) and various vegetable oils is now a well documented procedure (3-7). The purpose of this technique is to produce original structured fats with properties different from a simple blending, that may be used as spreads or introduced into pastry. The new fats contain higher amounts of polyunsaturated fatty acids (PUFA) than butter, which provides health benefits (8,9). To our knowledge only a few authors associated AMF fractionation with blending and interesterification (10,11), although this combination may be used to increase the ratio of vegetable oil in blends and thus the PUFA content of the product. The compositional changes occurring during the lipase-catalysed interesterification of AMF/rapeseed oil (RO) and AMF stearin fraction (AMFSF)/RO blends were described in the first part of this study. In the present and second part are reported the resulting changes in physical properties, especially the melting behaviour through solid fat content (SFC), dropping point (DP) and fusion profiles by differential scanning calorimetry (DSC). [less ▲]

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