References of "Blecker, Christophe"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailFluorescence spectroscopy coupled with factorial discriminant analysis technique to identify sheep milk from different feeding systems.
Hammami, M.; Rouissi, H.; Salah, N. et al

in Food Chemistry (2010)

Detailed reference viewed: 22 (6 ULg)
Full Text
Peer Reviewed
See detailMilk fat globule membrane and buttermilks: from composition to valorization
Vanderghem, Caroline ULg; Bodson, Pascal; Danthine, Sabine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(3), 485-500

Buttermilk, the by-product from butter manufacture, is low cost and available in large quantities but has been considered for many years as invaluable. However, over the last two decades it has gained ... [more ▼]

Buttermilk, the by-product from butter manufacture, is low cost and available in large quantities but has been considered for many years as invaluable. However, over the last two decades it has gained considerable attention due to its specific composition in proteins and polar lipids from the milk fat globule membrane (MFGM). The aim of this review is to take stock of current buttermilk knowledge. Firstly, the milk fat globule membrane composition and structure are described. Secondly, buttermilk and its associated products are defined according to the milk fat making process. Structure and mean composition of these products are summarized from recent dairy research data and related to technological properties, especially the emulsifying properties provided by MFGM components. Finally, new applications are presented, leading to promising valorizations of buttermilk and its derivate products. [less ▲]

Detailed reference viewed: 79 (43 ULg)
Full Text
Peer Reviewed
See detailLa steam explosion : application en tant que prétraitement de la matière cellulosique
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(Spécial N°2),

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the ... [more ▼]

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose cristallinity rate,…), hydrolysis of hemicellulosic components (mono and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels or high value-added molecules process. [less ▲]

Detailed reference viewed: 102 (43 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 54 (9 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 75 (35 ULg)
Full Text
Peer Reviewed
See detailOptimisation of xanthan gum production by palm date (Phoenix dactylifera L.) juice by-products using response surface methodology
Ben Salah, Riadh; Chaari, Kacem; Besbes, Souhail et al

in Food Chemistry (2010), 121(2), 627-633

The present study was undertaken investigate and optimise the possibility of xanthan gum production by Xanthomonas campestris NRRL B-1459 in batch experiments on date palm juice by-products. Using an ... [more ▼]

The present study was undertaken investigate and optimise the possibility of xanthan gum production by Xanthomonas campestris NRRL B-1459 in batch experiments on date palm juice by-products. Using an experimental Response Surface Methodology complemented with a Central Composite Orthogonal Design, three major independent variables (date juice carbon source, nitrogen source and temperature) were evaluated for their individual and interactive effects on biomass and xanthan gum production. The optimal conditions selected were: 84.68 g/l for carbon source, 2.7 g/l for nitrogen source, and 30.1 degrees C for temperature. The experimental value obtained for xanthan production under these conditions was about 43.35 g/l, which was close to the 42.96 g/l value predicted by the model. Higher yields of biomass production could be obtained at 46.68 g/l for carbon source, 4.58 g/l for nitrogen source and 30 degrees C for temperature. The maximum value obtained for biomass production was 3.35 g/l, which was higher than the 2.98 g/l value predicted by the model. The xanthan formed was subjected to HPLC and TLC analyses and its molecular weight as well as pyruvate content were identified. The findings indicated that this polysaccharide contained glucose, glucoronic acid and mannose. Overall, the date palm juice by-products presented in the current study seem to exhibit promising properties that can open new pathways for the production of efficient and cost-effective xanthan gum. (C) 2010 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 806 (1 ULg)
Full Text
Peer Reviewed
See detailRheological and physical properties of date juice palm by-product (phoenix dactylifera L.) and commercial xanthan gums.
Ben Salah, Riadh; Besbes, Souhail; Chaari, Kacem et al

in Journal of Texture Studies (2010), 41(2), 125-138

Rheological and thermal properties of xanthan produced by Xanthomonas campestris from date by-products (DBP-xanthan) and commercial xanthan were determined. DBP-xanthan gave solutions with lower apparent ... [more ▼]

Rheological and thermal properties of xanthan produced by Xanthomonas campestris from date by-products (DBP-xanthan) and commercial xanthan were determined. DBP-xanthan gave solutions with lower apparent viscosity than commercial xanthan. However, DBP-xanthan solutions were more stable to temperature changes and ionic strength than commercial xanthan. Gradual increase of storage modulus (G') as function of frequency was observed for the two polysaccharides. On the other hand, loss modulus (G ') remained constant for DBP-xanthan and an increase was observed for commercial xanthan. Granulometric profile indicates that DPB-xanthan particle size was lower than commercial xanthan. Differential scanning calorimetry showed that the melting temperatures (T-m) and enthalpy (Delta H-m) of DBP-xanthan were higher than those of commercial xanthan. These properties of DBP-xanthan are quite rare among xanthan described in the literature and give this new gum great potential for use in the field of bioindustries as thickening and stabilizing agents. PRACTICAL APPLICATIONS Xanthan gum from date by-products (DBP-xanthan) was recently produced in our laboratory. No work has been undertaken to study the rheological properties of this polysaccharide to date. Rheological and some physicals properties were compared to those of commercial xanthan. This could promote industrial use of DBPs as low-cost natural source for xanthan gum production. [less ▲]

Detailed reference viewed: 320 (5 ULg)
Full Text
Peer Reviewed
See detailDate Fiber Concentrate: Chemical Compositions, Functional Properties and Effect on Quality Characteristics of Beef Burgers
Besbes, Souhail; Ghorbel, Raoudha; Ben Salah, Riadh et al

in Journal Of Food And Drug Analysis (2010), 18(1), 8-14

Chemical composition of second-grade dates (with hard texture) from Tunisian Deglet Nour cultivar was similar to that of commercial dates. Date fiber concentrate (DFC) was extracted and characterized in ... [more ▼]

Chemical composition of second-grade dates (with hard texture) from Tunisian Deglet Nour cultivar was similar to that of commercial dates. Date fiber concentrate (DFC) was extracted and characterized in terms of chemical composition and techno-functional properties. DFC showed interesting functional properties. In fact, it presented high water binding capacities (WBC) and oil binding capacities (OBC) reaching 15.82 g/g and 11.31 g/g, respectively. These Values were higher than those reported for the most fruits and vegetable fiber concentrates. The use of DFC in beef burger formulations improves cooking properties, e.g. increase cooking yield and decrease shrinkage and minimize production Cost Without negatively affecting their sensory properties. Results indicate the potentially functional and economic utility Of Phoenix L. Flesh from dry dates as new source of dietary fiber. [less ▲]

Detailed reference viewed: 98 (4 ULg)
Full Text
Peer Reviewed
See detailPreparation and characterization of jellies with reduced sugar content from date (Phoenix dactylifera L.) and lemon (Citrus limon L.) by-products
Masmoudi, Manel; Besbes, Souhail; Blecker, Christophe ULg et al

in Fruits (2010), 65(1), 21-29

Introduction. The increase in diabetes and obesity has increased the demand for reduced sugar products such as jams and jellies. Four jelly formulations were prepared using date juice which was enriched ... [more ▼]

Introduction. The increase in diabetes and obesity has increased the demand for reduced sugar products such as jams and jellies. Four jelly formulations were prepared using date juice which was enriched with pectin and lemon flavors. Materials and methods. Reduced quantities of sugars (45% and 55%) were added to the juice at different pH (3 and 3.5). The prepared jellies were evaluated for physico-chemical and sensory properties. Results and discussion. The water activity values for jellies ranged between 0.767 and 0.804, making them safe from the development of the majority of bacteria. The addition of less quantity of sugar, as well as the decreased pH, resulted in significantly firmer jellies, with higher adhesiveness, chewiness and cohesiveness. Sensory evaluation showed that the prepared jellies averaged 4.17-5.47 and 4.59-5.67 for taste and firmness, respectively, in a 7-point hedonic scale consumer acceptance study. The most appreciated jellies were those prepared with the lowest sugar content, with a slight preference for that with a pH of 3.5. Significant differences were not found between scores for the other sensory attributes (color, transparency, brightness, odor and springiness). [less ▲]

Detailed reference viewed: 56 (1 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 85 (12 ULg)
Full Text
Peer Reviewed
See detailApplication of steam explosion for the pretreatment of the lignocellulosic raw materials
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(2), 561-566

Application of steam explosion for the pretreatment of the lignocellulosic raw materials. Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural ... [more ▼]

Application of steam explosion for the pretreatment of the lignocellulosic raw materials. Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose cristallinity rate,.), hydrolysis of hemicellulosic components (mono-and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels or high value-added molecules process. [less ▲]

Detailed reference viewed: 66 (7 ULg)
Full Text
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 ▲]

Detailed reference viewed: 19 (6 ULg)
Full Text
See detailDéveloppements alimentaires: la demande guide l'innovation
Blecker, Christophe ULg

Scientific conference (2009, November 18)

Detailed reference viewed: 4 (2 ULg)
Full Text
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 ▲]

Detailed reference viewed: 255 (44 ULg)
Full Text
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 ▲]

Detailed reference viewed: 136 (38 ULg)
Full Text
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 ▲]

Detailed reference viewed: 117 (36 ULg)
Full Text
See detailEvolution of food design: from recipe to formulation concept
Blecker, Christophe ULg

Conference (2009, July)

Detailed reference viewed: 19 (5 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 117 (53 ULg)