References of "Blecker, Christophe"
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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Récents Progrès en Génie des Procédés (2011), 101

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor ... [more ▼]

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor (SF), based on the residence time and the process temperature. The results obtained show that thermal degradation of cellulose fibers is limited when the severity factor value is below 4.0. At higher intensities, determination of thermal degradation products shows a significant increase of the hydroxymethylfurfural (5-HMF) amount when increasing the intensity of the treatment. When the severity factor reached 5.2, TGA analysis shows that the increase of degradation products is coupled to an increase of the char level meaning a strong degradation of the cellulose. [less ▲]

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See detailCombination of lipase catalysis and thiol-Michael addition for the synthesis of carbohydrate esters used as stabilizers in supercritical carbon dioxide emulsions
Boyère, Cédric ULg; Favrelle, Audrey; Broze, Guy ULg et al

Poster (2011, November 21)

The use of aqueous dispersed media, such as emulsions and miniemulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental ... [more ▼]

The use of aqueous dispersed media, such as emulsions and miniemulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental impact, ease of products recovery and increased reaction rate. Although, dispersed media are usually implemented from water/solvent mixtures, supercritical carbon dioxide (scCO2) (Pc =74 bars; Tc = 31°C) constitutes an interesting alternative to the traditional organic solvents because it is inexpensive, non-toxic, non-flammable and environmentally friendlier. In this context, we develop a novel class of surface active compounds able to stabilize water/scCO2 emulsions, i.e. fluorinated modified carbohydrates. The hydrophilic head of the surfactant consists in a sugar moiety whereas the fluorinated tail has a strong affinity for the scCO2 phase. These carbohydrate esters are prepared by a two-step strategy which takes advantage of the selectivity of enzymatic catalysis and the versatility of the thiol-Michael addition reaction. The new thiolated mannose intermediate is a useful building block for the incorporation of unprotected sugar moieties into complex molecules. The surface active properties of the fluorinated derivatives have been evaluated as well as their use as stabilizers for the preparation of microparticles and highly porous polymer materials in scCO2. [less ▲]

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See detailKinetics of the hydrolysis of polysaccharide galacturonic acid and neutral sugars chains from flaxseed mucilage
Happi Emaga, Thomas; Rabetafika, Holy-Nadia ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), (2012 16(2)), 139-147



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See detailLipase catalysis and thiol-Michael addition: a relevant association for the synthesis of new surface active carbohydrate esters
Boyère, Cédric ULg; Favrelle, Audrey ULg; Broze, Guy ULg et al

in Carbohydrate Research (2011), 346(14), 2121-2125

A novel class of surface-active carbohydrate esters is prepared by a two-step strategy that takes advantage of the selectivity of enzymatic catalysis and the versatility of the thiol-Michael addition ... [more ▼]

A novel class of surface-active carbohydrate esters is prepared by a two-step strategy that takes advantage of the selectivity of enzymatic catalysis and the versatility of the thiol-Michael addition reaction. The surfactant performance of the produced aliphatic, fluorinated and silicon based sugar esters are evaluated by surface tension measurements. The novel thiolated mannose, made available in this work, appears as a powerful building block for the incorporation of unprotected sugar moieties into complex molecules. [less ▲]

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See detailChemical composition and functional properties of Ulva lactuca seaweed collected in Tunisia
Yaich, H.; Garna, H.; Besbes, S. et al

in Food Chemistry (2011), 128(4), 895-901

The chemical composition and some functional properties of the dried "Ulva lactuca" algae, collected from the littoral between the Taboulba and Sayada area, were determined. The dried "U. lactuca" algae ... [more ▼]

The chemical composition and some functional properties of the dried "Ulva lactuca" algae, collected from the littoral between the Taboulba and Sayada area, were determined. The dried "U. lactuca" algae were investigated for their soluble, insoluble and total dietary fibre content, mineral amount, amino acid and fatty acid profiles, swelling capacity (SWC), water holding capacity (WHC) and oil holding capacity (OHC). Results showed that "U. lactuca" alga powder was characterised by a high content of fibres (54.0%), minerals (19.6%), proteins (8.5%) and lipids (7.9%). The neutral fibres contain hemicellulose (20.6%), cellulose (9.0%) and lignin (1.7%). The proteinic fraction analysis indicated the presence of essential amino acids, which represent 42.0% of the total amino acids. The fatty acids profile was dominated by the palmitic acid, which represents about 60.0% of the total fatty acids, followed by oleic acid (16.0%). The study of the functional properties proved that SWC, WHC and OHC of this alga varied with temperatures and that were comparable to those of some commercial fibre rich products. (C) 2011 Elsevier Ltd. All rights reserved. [less ▲]

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See detailDe la complexité de l'aliment à la technologie d'assemblage
Blecker, Christophe ULg

Scientific conference (2011, October 04)

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See detailScreening of Basic Properties of Amphiphilic Molecular Structures for Colloidal System Formation and Stability. The Case of Carbohydrate-Based Surfactants
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Paquot, Michel ULg

in In Amphiphiles: Molecular Assembly and Applications; Nagarajan, R. (2011)

Colloidal systems are bubbles, droplets, or/and particles dispersed in a continuous media, which are encountered in nature, biological system, and manufactured products. As site of interfaces between at ... [more ▼]

Colloidal systems are bubbles, droplets, or/and particles dispersed in a continuous media, which are encountered in nature, biological system, and manufactured products. As site of interfaces between at least two bulk phases, their formation and stability need the presence of amphiphilic molecules. Carbohydrate-based surfactants (CBS) take part of these groups of compound having numerous attractive features: an abundance of precursor raw material sources, an excellent environmental compatibility, and a possible quasi-unlimited design of their molecular structure and geometry by different preparation routes. Numerous properties and activities including the aptitude to form and stabilize colloidal systems are therefore expected from a wide range of CBS compounds. Screening of their interfacial behaviors, which govern their functionalities in colloidal system properties, are then relevant in fundamental and practical point of view. In this chapter, interfacial properties of uronic acid-based surfactants are presented as examples of screening approaches. Experimental measurements of both dynamic and equilibrium properties at air-liquid and liquid-liquid interfaces, as well as a computational approach are reported. [less ▲]

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See detailScreening of Basic Properties of Amphiphilic Molecular Structures for Colloidal System Formation and Stability: The Case of Carbohydrate-Based Surfactants
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Paquot, Michel ULg

in Nagarajan, Ramananthan (Ed.) Amphiphiles: Molecular Assembly and Applications (2011, September 19)

Colloidal systems are bubbles, droplets, or/and particles dispersed in a continuous media, which are encountered in nature, biological system, and manufactured products. As site of interfaces between at ... [more ▼]

Colloidal systems are bubbles, droplets, or/and particles dispersed in a continuous media, which are encountered in nature, biological system, and manufactured products. As site of interfaces between at least two bulk phases, their formation and stability need the presence of amphiphilic molecules. Carbohydrate-based surfactants (CBS) take part of these groups of compound having numerous attractive features: an abundance of precursor raw material sources, an excellent environmental compatibility, and a possible quasi-unlimited design of their molecular structure and geometry by different preparation routes. Numerous properties and activities including the aptitude to form and stabilize colloidal systems are therefore expected from a wide range of CBS compounds. Screening of their interfacial behaviors, which govern their functionalities in colloidal system properties, are then relevant in fundamental and practical point of view. In this chapter, interfacial properties of uronic acid-based surfactants are presented as examples of screening approaches. Experimental measurements of both dynamic and equilibrium properties at air-liquid and liquid-liquid interfaces, as well as a computational approach are reported. [less ▲]

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See detailInfluence of the processing parameters on the physicochemical properties of puff pastry margarines
Lefebure, Emilie ULg; Ronkart, Sébastien; Brostaux, Yves ULg et al

Poster (2011, September 18)

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See detailEffect of steam explosion pre-treatment on enzymatic saccharification of lignocellulosic material
Meyer, Laurence ULg; Jacquet, Nicolas ULg; Vanderghem, Caroline ULg et al

Poster (2011, September 08)

Taking into account the sharp rise in prices and the depletion of resources of petroleum, an alternative to fossil resources is needed. A probable alternative is the use of lignocellulosic raw material to ... [more ▼]

Taking into account the sharp rise in prices and the depletion of resources of petroleum, an alternative to fossil resources is needed. A probable alternative is the use of lignocellulosic raw material to produce biofuels. The “first generation” biofuels are highly controversial because of the use of food plant material. The aim of the “second generation” biofuels is to take lignocellulosic non-food plant material as raw material. Lignocellulosic biomass has a very complex structure made of linkages between lignins, cellulose and hemicelluloses. The saccharification of these lignocellulosic materials requires the fractionation of its constituents. Research has lead to many lignocellulosic biomass fractionation pre-treatments. This study particularly focuses on the steam explosion pretreatment followed by an enzymatic saccharification. Steam explosion is a thermomechanical process which allows the breakdown of the lignocellulosic material structure by the combined action of steam heating, hydrolysis induced by the organic acids formed during the process and shear stress resulting from the pressure rough drop. This treatment leads to modification of the physical parameters such as water retention capacity, cristallinity rate of the cellulosic fraction, hydrolysis of the hemicellulosic fraction and rearrangement in the lignin structure. Such modifications are supposed to make cellulose enzymatic hydrolysis from complex lignocellulosic material easier. In order to verify this hypothesis, different lignocellulosic raw materials have been pre-treated by steam explosion. These materials were sugar beet pulp, corn straw and miscanthus. In order to check the effect of steam explosion pre-treatment on cellulose, a microcrystalline cellulose was also treated. Steam explosion was performed at a vapor pressure of 18 bars and with a retention time of 2 minutes. The steam exploded lignocellulosic materials and the untreated one were submitted to a hydrolysis with a mixture of enzymes composed of cellulases and cellobiase activities during 24 hours. The quantification of glucose in the hydrolysates at different times was performed by HPAEC-PAD. Rate of cellulose converted into glucose were better with steam exploded raw material showing that steam explosion allows improvement of lignocellulosic material for enzymatic saccharification. [less ▲]

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See detailInfluence of steam explosion on the thermal stability of cellulose fibres
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Polymer Degradation & Stability (2011), 96

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which ... [more ▼]

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. [less ▲]

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See detailEnzymatic Interesterificationof Palm oil and Fractions: A Calorimetric Study
Danthine, Sabine ULg; De Clercq, Nathalie; Lefebure, Emilie ULg et al

Poster (2011, September)

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See detailEFFECT OF DATE FLESH FIBER CONCENTRATE ADDITION ON DOUGH PERFORMANCE AND BREAD QUALITY
Borchani,, Chema; Masmoudi, Manel; Besbes, Souhail et al

in JOURNAL OF TEXTURE STUDIES (2011), 42(4), 300-308

Date flesh fiber concentrate (DFFC) of Deglet Nour variety were extracted and incorporated in a bakery product. Dough rheological characteristics showed that water absorption, stability, index quality ... [more ▼]

Date flesh fiber concentrate (DFFC) of Deglet Nour variety were extracted and incorporated in a bakery product. Dough rheological characteristics showed that water absorption, stability, index quality, resistance to deformation increased with the amount of added fiber, whereas degree of softening and extensibility decreased in all levels of fiber. Bread evaluation revealed that DFFC addition caused an increase of bread yield especially for the highest levels, a change of crumb color and an insignificant decrease of bread volume. Breads are subjected to sensory evaluation for odor, taste, crumb color, crumb smoothness and overall acceptability. Significant differences were not found (P > 0.05) between scores for all sensory parameters. [less ▲]

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See detailMonolayer Properties of Uronic Acid Bicatenary Derivatives at the Air-Water Interface: Effect of Hydroxyl Group Stereochemistry Evidenced by Experimental and Computational Approaches
Razafindralambo, Hary ULg; Richel, Aurore ULg; Wathelet, Bernard ULg et al

in Physical Chemistry Chemical Physics [=PCCP] (2011), 13(33), 1529115298

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water ... [more ▼]

By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air–water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuirfilmbalance, Brewster angle microscopy, and ellipsometry at 20°C reveal that the derivative of glucuronate (C14/14–GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C14/14–GalA). Both films are very mechanically resistant (compression modulus > 300m Nm-1) and stable (collapse pressure exceeding 60mNm-1), while that of C14/14–GalA exhibits a very high compression modulus up to 600mNm-1 like films in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Differences in the molecular conformation and film behaviours of uronic acid bicatenary derivatives at the air–water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C14/14–GalA) than in the equatorial position (C14/14–GlcA). [less ▲]

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See detailEnzymatic synthesis and surface active properties of novel hemifluorinated mannose esters
Favrelle, Audrey ULg; Boyère, Cédric ULg; Laurent, Pascal ULg et al

in Carbohydrate Research (2011), 346(9), 1161-1164

The lipase-catalysed esterification of sugars with hemifluorinated acid derivatives is reported for the first time. A series of mannose modified derivatives having fluorinated chains with different length ... [more ▼]

The lipase-catalysed esterification of sugars with hemifluorinated acid derivatives is reported for the first time. A series of mannose modified derivatives having fluorinated chains with different length have been prepared accordingly in moderate yield. A preliminary evaluation of the surface active properties of these hemifluorinated mannose esters revealed their ability to reduce the surface tension of water much more efficiently than their aliphatic counterparts. [less ▲]

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