References of "Blecker, Christophe"
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See detailEffect of physicochemical characteristics of cellulosic substrates on enzymatic hydrolysis by means of a multi-stage process for cellobiose production
Vanderghem, Caroline ULg; Jacquet, Nicolas ULg; Danthine, Sabine ULg et al

in Applied Biochemistry and Biotechnology (2012), 166(6), 1423-1432

The effect of two types of cellulose, microcrystalline cellulose and paper pulp, on enzymatic hydrolysis for cellobiose production was investigated. The particle size, the relative crystallinity index and ... [more ▼]

The effect of two types of cellulose, microcrystalline cellulose and paper pulp, on enzymatic hydrolysis for cellobiose production was investigated. The particle size, the relative crystallinity index and the water retention value were determined for both celluloses. A previously studied multistage hydrolysis process that proved to enhance the cellobiose production was studied with both types of celluloses. The cellobiose yield exhibited a significant improvement (120% for the microcrystalline cellulose and 75% for the paper pulp) with the multistage hydrolysis process compared to continuous hydrolysis. The conversion of cellulose to cellobiose was greater for the microcrystalline cellulose than for the paper pulp. Even with high crystallinity, microcrystalline cellulose achieved the highest cellobiose yield probably due to its highest specific surface area accessible to enzymes and quantity of adsorbed protein. [less ▲]

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See detailCarbohydrate-based surfactants: structure-activity relationships
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Paquot, Michel ULg

in Nawaz, Zeeshan; Naveed, Shahid (Eds.) Advances in Chemical Engineering (2012)

The aim of the present contribution is: (1) to review CBS in terms of structural classification based on their molecular size (mono-, oligo-, polymeric surfactants), geometry (standard, bipolar or ... [more ▼]

The aim of the present contribution is: (1) to review CBS in terms of structural classification based on their molecular size (mono-, oligo-, polymeric surfactants), geometry (standard, bipolar or bolaform, and gemini surfactants), and the nature of the polar headgroup (charged or not, cyclic or not), the apolar tail (number and length of alkyl chain), and the linker (amide, ester, ...) and/or the spacer; (2) to present systematically results on structure- activity relationships of uronic acid derivatives (UADs), a particular class of carbohydrate-based surfactants. These concern the impact of each structural entity including the polar headgroup (stereochemistry), apolar tail (chain length, number, and unsaturation), and linkage/spacer, on the performance of UADs to change surface properties, and possibly, to form and stabilize colloidal systems. [less ▲]

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See detailContribution to the study of physicochemical and functional properties of hemicelluloses and xylooligosaccharides (XOS) extracted from rapeseed meal
Mertens, Cécile ULg; Paquot, Michel ULg; Destain, Jacqueline ULg et al

Poster (2012, February 08)

Rapeseed meal is one of the main industrial co-products from agriculture in Belgium, with more than 30 000 T produced each year. Beside its agricultural and energetic applications, new paths of ... [more ▼]

Rapeseed meal is one of the main industrial co-products from agriculture in Belgium, with more than 30 000 T produced each year. Beside its agricultural and energetic applications, new paths of valorization are being developed in order to add value to the rapeseed meal, usually by extraction of interesting molecules. In this thesis project, the aimed molecules are hemicelluloses, which are obtained via a global fractionation method that is being developed and optimized, constituting the first part of this project. Indeed, while rapeseed meals are globally already well exploited (mainly for their feed value), rapeseed hemicelluloses have not yet been studied for food application. Yet, hemicelluloses can be used as food additives (thickener, stabilizer, etc) mainly in bakery products. The literature being incomplete regarding the chemical structure of rapeseed hemicelluloses, one of the objectives of this project is to study their physicochemical properties, in regard with their technofunctional properties. Rapeseed hemicelluloses can also be used as raw material to produce an emergent type of prebiotic: xylooligosaccharides (XOS). These molecules can be introduced as well in the food supplement sector. Their production will be achieved by enzymatic hydrolysis, for a polymerization degree between two and five. Thus, the production and the physicochemical and technofunctional characterization of rapeseed XOS constitute the last objective of this project. This thesis is part of the SYNBIOFOR project, which aim is to create new symbiotic ingredients. [less ▲]

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See detailScaphandre La science rencontre l'art: L'art
Haubruge, Eric ULg; Bay, Daniel ULg; Semal, Jean et al

in Haubruge, Eric; Bay, Daniel; Semal, Jean (Eds.) Scaphandre La science rencontre l'art (2012)

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See detailInfluence of the water content in the synthesis of fructose laurate by immobilized lipase B of Candida antarctica (Novozym 435)
Olive, Gilles ULg; Pompeu Torezan, Gabriela A.; Blecker, Christophe ULg

in Bulletin de la Société Royale des Sciences de Liège (2012), 81(2012), 82-89

New synthesis conditions for a direct esterification of fructose by lauric acid with Novozym 435 as a catalyst are reported in this paper. With these new conditions, a conversion rate of 72% was achieved ... [more ▼]

New synthesis conditions for a direct esterification of fructose by lauric acid with Novozym 435 as a catalyst are reported in this paper. With these new conditions, a conversion rate of 72% was achieved, which is almost the same value as in the case of transesterification where no water as by-product is produced (74.6 %). The conversion rate of these reactions can be modeled as a function of the initial water content by a three-parameter power law for the esterification and by an exponential law for the transesterification. The influence of the water content on the mono over di-ester ratio will also be discussed to a lesser extent. [less ▲]

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See detailSynthèse enzymatique d'esters de fructose
Olive, Gilles ULg; Pompeu Torezan, Gabriela; Blecker, Christophe ULg

in Comptes Rendus Chimie (2012), 15(11-12), 1037-1047

The enzymatic synthesis of esters is well documented in the literature. A number of parameters have been revised to optimize the operating conditions, in view of a more industrial approach. The ... [more ▼]

The enzymatic synthesis of esters is well documented in the literature. A number of parameters have been revised to optimize the operating conditions, in view of a more industrial approach. The experimental conditions presented here are now superior to those of literature and the yields of esters show 78% of fructose laurate. Analytical methods have been perfected and rapid methods (based on different TLC conditions depending on the desired information), accurate methods (based on HPLC) and several purification methods were developed. [less ▲]

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See detailCharacterization of by-products from cooked fruit processing and potential use in food products
Aguedo, Mario ULg; Kohnen, Stephan; Rabetafika, Holy-Nadia ULg et al

in Journal of Food Composition and Analysis (2012), 27

The process that produces Lie`ge syrup (apple butter-like) results in high amounts of residues from cooked apples, pears and sun-dried dates. These unusual fruit by-products were studied for their ... [more ▼]

The process that produces Lie`ge syrup (apple butter-like) results in high amounts of residues from cooked apples, pears and sun-dried dates. These unusual fruit by-products were studied for their composition in total proteins and fats, dietary fiber (DF) and their content in total and free monosaccharides. All three by-products contained around 20% of total non-cellulosic monosaccharides and around 10% of free monosaccharides. According to two different methods, DF accounted for 70% of the dry weight (DW) with an insignificant soluble fraction; pectin represented 2–3% of DW. Apple and pear residues were composed mainly of cellulose, whereas lignin was the main fraction for dried date. The polyphenolic content and the antioxidant activity of the three products were also assessed and the values showed that their antioxidant characteristics were comparable to that of various raw fruits. No phenolic acids were detected, indicating that the cooking process resulted in their extraction. The lyophilized and ground residues exhibited high water holding capacities (between 5.2 g water per g DW for pear and 8.6 for apple) and average oil holding capacities (around 2.5 g oil per g DW), whereas their color was light brownish as shown by the L*, a*, b* coordinates determined. These data open the possibility to contemplate new specific and niche applications for such by-products. Besides, it provides information about the effects of a cooking process on apple and pear pomaces, as well as on an unusual residue from a dried fruit (date). [less ▲]

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See detailLes crèmes végétales : une alternative aux crèmes laitières
Anihouvi, Prudent; Danthine, Sabine ULg; Karamoko, G et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(3), 344-359

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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] (2012), 16(2), 139-147

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See detailEnzymatic process development for the extraction of ferulic acid from wheat bran
Giet, Jean-Michel ULg; Blecker, Christophe ULg

Poster (2012)

The agro-industries generate each year thousands of tons of by-products, such as cereal bran or sugar beet pulps. For instance, Walloon wheat transformation industry provides annually about 200.000 tons ... [more ▼]

The agro-industries generate each year thousands of tons of by-products, such as cereal bran or sugar beet pulps. For instance, Walloon wheat transformation industry provides annually about 200.000 tons of bran. Most of those by-products are under-valorized as cattle feed. By the use of biorefinery, this biomass may constitute a renewable source for various value-added molecules like dietary fibres, proteins, antioxidants, and more. [less ▲]

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See detailL'homme produit - L'alimentation
Blecker, Christophe ULg

in Haubruge, Eric; Bay, Daniel; Semal, Jean (Eds.) Scaphandre - La science rencontre l'art (2012)

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See detailLiquid Crystalline Phases Induced by the Hydroxyl Group Stereochemistry of Amphiphilic Carbohydrate Bicatenary Derivatives
Razafindralambo, Hary ULg; Richel, Aurore ULg; Paquot, Michel ULg et al

in Journal of Physical Chemistry B (2012), 116(13), 3998-4005

Liquid-crystals (LC) may exist in different phases depending upon the orientational and positional orders of molecules in the material. Here, we demonstrate that the class of LC state induced by ... [more ▼]

Liquid-crystals (LC) may exist in different phases depending upon the orientational and positional orders of molecules in the material. Here, we demonstrate that the class of LC state induced by amphiphilic carbohydrate bicatenary derivatives is strictly a hydroxyl group stereochemistry-dependent. This statement results from the experimental and theoretical investigations of surface film (2D) and bulk solid (3D) thermal behavior of synthetic stereoisomers n-tetradecyl (-D-n-tetradecyl) galacto- and gluco-pyranosiduronate, with an axial (GalA-C14/14) or equatorial (GlcA-C14/14) hydroxyl group at the fourth carbon, respectively. Surface pressure-area isotherms (283 K to 310 K), differential scanning calorimetry thermograms (223 K to 573 K), and polarized optical textures (298-363 K) reveal that GlcA-C14/14 organizes as a smectic LC-like phase (positional or lateral order) whereas the analogous stereoisomeric GalA-C14/14 behaves as a nematic LC-like phase (orientational order). Thermodynamic investigations and molecular dynamics models computed under similar temperature conditions provide consistent data with physical properties resulting from experimental approaches. [less ▲]

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See detailImpact of formic/acetic acid and ammonia pre-treatments on chemical structure and physico-chemical properties of Miscanthus x giganteus lignins
Vanderghem, Caroline ULg; Richel, Aurore ULg; Jacquet, Nicolas ULg et al

in Polymer Degradation & Stability (2012), 96(10), 1761-1770

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these ... [more ▼]

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these fractionation processes on chemical structure, physico-chemical properties and antioxidant activity of extracted lignins were investigated. Lignins were characterized by their purity, carbohydrate composition, thermal stability, molecular weight and by Fourier transform infrared (FTIR), 1H and quantitative 13C nuclear magnetic resonance (NMR), adiabatic broadband {13C-1H} 2D heteronuclear (multiplicity edited) single quantum coherence (g-HSQCAD). The radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) was also investigated. Formic/acetic acid pretreatment performed in milder conditions (80° C for 3 h) gave a delignification percentage of 44.7% and soaking in aqueous ammonia 36.3%. Formic/acetic acid pretreatment performed in harsh conditions (107°C for 3 h) was more effective for extensive delignification (86.5%) and delivered the most pure lignin (80%). The three lignin fractions contained carbohydrate in different extent: 3% for the lignin obtained after the formic/acetic acid pretreatment performed at 107 C (FAL-107), 5.8% for the formic/acetic acid performed at 80°C (FAL-80) and 13.7% for the ammonia lignin (AL). The acid pretreatment in harsh conditions (FAL-107) resulted in cleavage of b-O-4' bonds and aromatic C-C. Repolymerisation was thought to originate from formation of new aromatic C-O linkages. Under milder conditions (FAL-80) less b-O-4' linkages were broken and repolymerisation took place to a lesser extent. Ammonia lignin was not degraded to a significant extent and resulted in the highest weight average 3140 g mol -1. Despite the fact of FAL-107 repolymerisation, significant phenolic hydroxyls remained free, explaining the greater antioxidant activity. [less ▲]

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See detailAgronomical factors influencing the legumin/ vicilin ratio in pea (Pisum sativum L.) seeds
Mertens, Cécile ULg; Dehon, Lydie; Bourgeois, Audrey et al

in Journal of the Science of Food and Agriculture (2012)

BACKGROUND: Many research studies have investigated the impact of agronomical factors on the protein content of pea (Pisum sativum). This study aimed to establish if a correlation exists between protein ... [more ▼]

BACKGROUND: Many research studies have investigated the impact of agronomical factors on the protein content of pea (Pisum sativum). This study aimed to establish if a correlation exists between protein content and legumin/vicilin (L/V) ratio in pea seeds and to identify agronomical factors that have an impact on this ratio. RESULTS: The L/V ratio was positively correlated with protein content (r = 0.58, P ≤ 0.01), but no linear regression was applicable (adjusted R² = 0.31). Both variety and cultivation year had a highly significant effect on the ratio (P < 0.001). The interaction between these two factors was also highly significant (P < 0.001), some varieties being less sensitive to climatic conditions than others. Cultivation location had a highly significant effect (P < 0.01). There was no interaction between variety and location. Seeding density had a highly significant effect on the ratio (P < 0.01),with a saturation effect above 60 seeds/m². CONCLUSION: Further studies should establish if a linear regression model can be applied to pea varieties independently. Varieties with a stable L/V ratio can prove to be useful in the food industry. Other agronomical factors (soil type and seeding density) should be considered for the production of pea seeds with a specific L/V ratio. [less ▲]

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See detailOptimization of formic/acetic acid delignification of Miscanthus ×giganteus for enzymatic hydrolysis using response surface methodology
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

in Industrial Crops & Products (2012), 35

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus ×giganteus for ... [more ▼]

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus ×giganteus for enzymatic hydrolysis. The effects of three independent variables, namely cooking time (1, 2 and 3 h), formic acid/acetic acid/water ratio (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107 ◦C) on pulp yield, residual Klason lignin content, concentration of degradation products (furfural and hydroxymethylfurfural) in the black liquor, and enzymatic digestibility of the pulps were investigated. The major parameter influencing was the temperature for pulp yield, delignification degree, furfural production and enzymatic digestibility. According to the response surface analysis the optimum conditions predicted for a maximum enzymatic digestibility of the glucan (75.3%) would be obtained using a cooking time of 3 h, at 107 ◦C and with a formic acid/acetic acid/water ratio of 40/40/20%. Glucan digestibility was highly dependent on the delignification degree. [less ▲]

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See detailStructure, properties and obtention routes of flaxseed lignan secoisolariciresinol
Sainvitu, Pauline ULg; Nott, Katherine ULg; Richard, Gaetan ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(1), 115-124

Following a brief description of the structure and nomenclature of the lignan family, this review focuses on the flaxseed lignan secoisolariciresinol (SECO). The main properties, the analysis methods and ... [more ▼]

Following a brief description of the structure and nomenclature of the lignan family, this review focuses on the flaxseed lignan secoisolariciresinol (SECO). The main properties, the analysis methods and two routes for the preparation of SECO, i.e. extraction from renewable raw material and (hemi)-synthesis, are reviewed. Green methods recently developed for the first route and chemical syntheses inspired from biosyntheses for the second one are the main subjects of this paper. [less ▲]

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See detailDietary fibre characteristics and antioxydant activity of sesame seed coats
Elleuch, M.; Bedigian, D.; Besbes, S. et al

in International Journal of Food Properties (2011), 15(1), 25-37

The dietary fibre contained in the seed coats (testae) of sesame, by-products of the dehulling processes during the manufacture of sweetened sesame paste (halaweh), were evaluated with two assays: the ... [more ▼]

The dietary fibre contained in the seed coats (testae) of sesame, by-products of the dehulling processes during the manufacture of sweetened sesame paste (halaweh), were evaluated with two assays: the AOAC enzymatic-gravimetric method and the enzymatic-chemical method. Functional properties and antioxidant activity of sesame seed coats were also determined. The total, insoluble, and soluble dietary fibre contents measured were significantly higher using the AOAC method, than with the enzymatic-chemical method. The dietary fibre contained high amounts of neutral sugars (15.11 g/100 g seed coat dry matter), insoluble uronic acids (10.52 g/100 g seed coat dry matter), and lignin (5.42 g/100 g seed coat dry matter). Physical property analyses showed a high positive correlation between particle size reduction of seed coat, water holding capacity, and oil holding capacity; however, there was a negative correlation with bulk density. Sesame testae showed a relatively high polyphenol content (9.9 mg/g of seed coat dry matter). Aqueous methanol, ethanol, and acetone extracts of seed coats yielded similar polyphenol levels (75 mg/g of extract), higher than those found in aqueous extracts (52.7 mg/g of extract). Aqueous organic solvent extracts possessed higher antioxidant activity than water extracts. Our results suggested that sesame seed coats can be used in the preparation of low calorie, high fibre, and antioxidant-rich foods. [less ▲]

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

Poster (2011, December)

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités ... [more ▼]

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités des traitements appliqués ont été définies sur base d’un facteur de sévérité (SF), établi par une corrélation entre le temps de séjour et la température du process. Les résultats obtenus montrent que la dégradation thermique des fibres de cellulose reste limitée lorsque la valeur du facteur de sévérité est inférieure à 4.0. Aux intensités supérieures, le dosage des produits de dégradation montre une croissante importante des concentrations en hydroxyméthylfurfurals (5-HMF) dans les phases liquides issues des différents traitements. Lorsque la valeur du facteur de sévérité dépasse 5.2, les analyses TGA indiquent que l’augmentation des produits de dégradation est couplée à une croissance importante du taux de résidus carbonés, indiquant une forte dégradation thermique de la cellulose [less ▲]

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