References of "Paquot, Michel"
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See detailInfluence of Homogenization Treatment on Physicochemical 4 Properties and Enzymatic Hydrolysis Rate of Pure 5 Cellulose Fibers
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

in Applied Biochemistry and Biotechnology (in press)

The aim of this study is to compare the effect of different homogenization treat- 12 ments on the physicochemical properties and the hydrolysis rate of a pure bleached 13 cellulose. Results obtained show ... [more ▼]

The aim of this study is to compare the effect of different homogenization treat- 12 ments on the physicochemical properties and the hydrolysis rate of a pure bleached 13 cellulose. Results obtained show that homogenization treatments improve the enzymatic 14 hydrolysis rate of the cellulose fibers by 25 to 100 %, depending of the homogenization 15 treatment applied. Characterization of the samples showed also that homogenization had an 16 impact on some physicochemical properties of the cellulose. For moderate treatment inten- 17 sities (pressure below 500 b and degree of homogenization below 25), an increase of water 18 retention values (WRV) that correlated to the increase of the hydrolysis rate was highlighted. 19 Result also showed that the overall crystallinity of the cellulose properties appeared not to be 20 impacted by the homogenization treatment. For higher treatment intensities, homogenized 21 cellulose samples developed a stable tridimentional network that contributes to decrease 22 cellulase mobility and slowdown the hydrolysis process. [less ▲]

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See detailEnzymatic process for the fractionation of baker's yeast cell wall (saccharomyces cerevisiae)
Borchani, Chema; Fonteyn, Fabienne; Jamin, Guilhem et al

Conference (2014, April 07)

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See detailEffet des conditions d'extraction sur la composition et les activités antioxydantes des ulvanes de l'algue Ulva lactucas
Yaich, Hela; Garna, Haikel; Paquot, Michel ULg et al

Conference (2014, April 07)

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See detailLa relation structure chimique-propriétés physiques des galactomannanes extraits de la caroube
Gillet, Sébastien ULg; Blecker, Christophe ULg; Paquot, Michel ULg et al

in Comptes Rendus Chimie (2014), 17(4),

Carob galactomannan fine chemical structure is closely related to the physical behavior developed in aqueous solution. Three elements of structural characterization are mainly described in the literature ... [more ▼]

Carob galactomannan fine chemical structure is closely related to the physical behavior developed in aqueous solution. Three elements of structural characterization are mainly described in the literature: the degree of galactose substitution, chain length, and galactose units distribution. This review article will attempt to highlight the impact of different structural features on physical properties such as solubility, viscosity, formation of hydrogels or gels in combination with other saccharides. The impact of industrial purification process on the structure and physical properties is also developed. [less ▲]

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See detailImpact of extraction procedures on the chemical, rheological and textural properties of ulvan from Ulva lactuca of Tunisia coast
Yaich, Hela; Garna, Haikel; Besbes, Souhail et al

in Food Hydrocolloids (2014), (40), 53-63

The impact of the extraction conditions has been studied on the yield, chemical composition, rheological and textural properties of ulvan from the green seaweed Ulva lactuca. High ulvan yield was obtained ... [more ▼]

The impact of the extraction conditions has been studied on the yield, chemical composition, rheological and textural properties of ulvan from the green seaweed Ulva lactuca. High ulvan yield was obtained after combining enzymatic and chemical extraction but the lowest yield results at the drastic conditions (pH 1.5 and 90 C). Besides, solvent acidity was an important parameter controlling the ulvan extraction efficiency. The different extraction processes affected chemical composition of ulvan extracts and in particular, sulphate, ash and sugar contents. Low proportions of galactose, glucose and protein were also found in sulphated polysaccharides. The extract, which is resulted from combined enzymatic and chemical extraction, was mainly composed of high peak molecular weight polysaccharides. Ulvan hy-drocolloids demonstrated a pseudoplastic behavior. Viscoelastic behavior was carried out at a concen-tration of 1.6% (w/v) in the presence of 7 mM sodium tetraborate and at pH 7.5. However, polysaccharides formed a gel. It was not the case for the extract at pH 1.5 and 90 C under the same conditions. The results showed that a significant effect of the conditions of extraction on the textural characteristic (firmness, springiness and adhesiveness) of ulvan gels. [less ▲]

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See detailWater soluble exo-polysaccharide from Syncephalastrum racemosum, a strong inducer of plant defence reactions
Valepyn, Emmanuel ULg; Cabrera, Juan-Carlos; Richel, Aurore ULg et al

in Carbohydrate Polymers (2014), 101

This study examines the production, characterization and bioactivity on plant cell cultured in vitro of exopolysaccharides (EPS) from Syncephalastrum racemosum CBS 443.59. Firstly, the influence of the ... [more ▼]

This study examines the production, characterization and bioactivity on plant cell cultured in vitro of exopolysaccharides (EPS) from Syncephalastrum racemosum CBS 443.59. Firstly, the influence of the fungus culture condition in shake flasks (pH, temperature and different carbon and nitrogen sources) on EPS and biomass production were evaluated. In order to enhance EPS production, a new protocol based on two-stage pH fermentation in a 3 L stirred fermentor was developed. Under this condition, EPS production increased by 3.55 times, compared to a constant pH process, reaching a maximal EPS concentration of 2.62 g/L. Structurally, the EPS contains a polyglucuronic acid backbone, linked essentially with mannose and fucose units and some galactose and glucose units. The bioactivity of EPS as inducer of defence reactions in plant suspension-cultured cells was also studied. Our results show, for first time, that EPS from S. racemosum CBS 443.59 induces, depending on the concentration, PAL activation and H2O2 synthesis in Arabidospsis thaliana cell suspensions. [less ▲]

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See detailImpact of purification and fractionation process on the chemical structure and physical properties of locust bean gum
Gillet, Sébastien ULg; Blecker, Christophe ULg; Aguedo, Mario ULg et al

in Carbohydrate Polymers (2014)

Crude locust bean gum (CLBG) was purified and fractionated into two parts : the first was obtained by solubilization in water at 25 °C (GM25) and the second consisted in a further extraction at 80 °C on ... [more ▼]

Crude locust bean gum (CLBG) was purified and fractionated into two parts : the first was obtained by solubilization in water at 25 °C (GM25) and the second consisted in a further extraction at 80 °C on the residual impoverished fraction (GM80). The complete structural characterization has shown that GM80 possessed relatively longer chain lengths than GM25, a slightly lower degree of galactose substitution and a somewhat sharper galactosyl distribution in substituted and unsubstituted regions. A physical behavior analysis was carried out on solubilization kinetics, viscosity, viscoelasticity and formation of associated gels with xanthan or carrageenan. The average structure of GM80 generated larger intra-chain, inter-chain and inter-molecular interactions, resulting in the appearance of a stronger network. Small structural differences therefore generated very different physical behaviors. This study thus allowed to establish, in a precise and complete manner, fractionation-purification-structure-function relationships of galactomannans extracted from carob. [less ▲]

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See detailSynthese bibliographique de l'influence du procédé d'extraction et de purification sur les caractéristiques et les propriétés d'une gomme de caroube
Gillet, Sébastien ULg; Simon, mathilde; Paquot, Michel ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(1),

The carob tree is a species cultivated, in mediterranean countries, for its seeds. These seeds contain an endosperm rich in galactomannans used by the food industry for its texturing properties. After ... [more ▼]

The carob tree is a species cultivated, in mediterranean countries, for its seeds. These seeds contain an endosperm rich in galactomannans used by the food industry for its texturing properties. After harvesting, the seeds pass through a decutilation and a degermination. Cleaned endosperms are then milled to give crude locust bean gum. The purification step consists in a flour solubilization and then a precipitation of the galactomannans. Purification influences the characteristics of the resulting gum. The solubilization temperature is the parameter that affects the most on the final characteristics of the product. If it is hot or cold, galactomannans with different structural characteristics (and thus very different physical properties in aqueous solutions) will be selected. [less ▲]

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See detailComparative study of alkaline extraction process of hemicelluloses from pear pomace
Rabetafika, Holy-Nadia ULg; Bchir, Brahim ULg; Blecker, Christophe ULg et al

in Biomass & Bioenergy (2014), 61

Hemicelluloses were produced from pear pomace using direct alkaline extraction (sodium hydroxide and hydrogen peroxide) and two-step extraction with delignification pre-treatment (acidified sodium ... [more ▼]

Hemicelluloses were produced from pear pomace using direct alkaline extraction (sodium hydroxide and hydrogen peroxide) and two-step extraction with delignification pre-treatment (acidified sodium chlorite/sodium hydroxide). The aim of the study was to compare the extraction yield, composition and physicochemical characteristics of isolated hemicelluloses by size exclusion chromatography, FTIR and thermogravimetric analyses. Solid residues were analysed in order to evaluate the effect of processes on co-products (lignins and cellulose). Delignification of material (up to 995.4 g kg−1 of original lignins) during the direct alkaline hydrogen peroxide and two-step acidified sodium chlorite/sodium hydroxide processes improved the hemicellulose extraction yield attaining up to 945.3 g kg−1. Hemicelluloses were mainly composed of xylans (xylose/glucose ratio of 4.6–16.2) and had low lignin content (53.5–61.0 g kg−1 dry matter). Those from direct sodium hydroxide extraction were composed of xylans and glucans (xylose/glucose ratio of 1.5) with high content of lignins (149.3 g kg−1 dry matter). All isolated fractions were a mixture of polymers and oligomers with a molecular mass ranging from 1710 g mol−1 to 8 870 000 g mol−1. The two-step process gave the most pure cellulose residue (799.2 g kg−1 dry matter). According to results, the direct alkaline extraction with hydrogen peroxide was a promising process for the production of pure xylose-rich hemicelluloses from pear pomace solubilizing 802.2 g kg−1 of the original hemicelluloses but induced fragmentation of hemicelluloses. [less ▲]

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See detailOptimization of a formic/acetic acid delignification treatment on beech wood and its influence on the structural characteristics of the extracted lignins
Simon, Mathilde; Brostaux, Yves ULg; Vanderghem, Caroline ULg et al

in Journal of Chemical Technology & Biotechnology (2014), 89(1), 128-136

Background In order to replace petrochemicals by bio-based lignin products in a lot of high value-added applications, a formic/acetic acid treatment was adapted to beech wood (Fagus sylvatica L.) for ... [more ▼]

Background In order to replace petrochemicals by bio-based lignin products in a lot of high value-added applications, a formic/acetic acid treatment was adapted to beech wood (Fagus sylvatica L.) for lignin extraction. Results Beech wood particles were delignified at atmospheric pressure by a formic acid/acetic acid/water mixture. Cooking time and temperature were optimized for delignification, pulp yield and 2-furfural concentration. Response surface design analysis revealed that delignification yield increased with cooking time and temperature. Conclusion The multi-criteria optimization of delignification was used to find the ideal cooking conditions (5h07 min, 104.2°C) which could be satisfactory for the maximization of delignification (70.5%) and pulp yield (58.7%) and, to a lesser extent, for the minimization of 2-furfural production. Treatment conditions were found to influence the chemical structure of extracted lignins. Cooking time and temperature influenced inversely lignin molecular weights. [less ▲]

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See detailUse of lipases for the kinetic resolution of lactic acid esters in heptane or in a solvent free system
Richard, Gaetan ULg; Nott, Katherine ULg; Nicks, François et al

in Journal of Molecular Catalysis B : Enzymatic (2013), 97

tKinetic resolution of d,l-ethyl lactate (d,l-LA-Et) and d,l-butyl lactate (d,l-LA-Bu) was accomplished inthe presence of lipases. Transesterification of the lactate esters with alcohols was shown to be ... [more ▼]

tKinetic resolution of d,l-ethyl lactate (d,l-LA-Et) and d,l-butyl lactate (d,l-LA-Bu) was accomplished inthe presence of lipases. Transesterification of the lactate esters with alcohols was shown to be poorlyenantioselective, with a very low preference toward the l enantiomer. However, esterification of the freehydroxyl function of the lactate esters was much more enantioselective, with an opposite preferencetoward the d form. Among the 200 combinations screened (substrates and lipases), only two reactionsfulfilled the required criteria for an efficient resolution (fast reaction, enantioselectivity ratio higherthan 100). The best resolution was obtained by esterification of d,l-LA-Bu with butyric anhydride inthe presence of lipase B from Candida antarctica (CAL-B) in heptane (at 30◦C): LA-Bu was resolved in6 h with an initial esterification rate of d-LA-BU of 1.5 g L−1h−1g−1EZ, an enantioselectivity ratio higherthan 100, a l substrate consumption lower than 1%, and a final substrate enantiomeric excess superiorto 99%. After having demonstrated that neither LA-Bu nor BuAn were inhibitors of CAL-B, the reactionwas further improved by carrying it out in a solvent free system, at an elevated temperature (60◦C), andat a higher lipase concentration. LA-Bu was resolved in 6 h with an initial rate of 7.6 g L−1h−1g−1EZ, anenantioselectivity ratio higher than 100, and a final substrate enantiomeric excess of 95%. [less ▲]

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See detailImpact d'un fractionnement soustractif sur la relation structure-fonction de la gomme de caroube
Gillet, Sébastien ULg; Blecker, Christophe ULg; Aguedo, Mario ULg et al

Poster (2013, July 02)

Le choix d'une température de fractionnement de la gomme de caroube va conditionner les caractéristiques des fractions obtenues et par conséquent les potentialité d'applications de ces dernières.

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See detailEffect of Pear, Apple and Date Fibres from Cooked Fruit By-products on Dough Performance and Bread Quality
Bchir, Brahim ULg; Rabetafika, Holy-Nadia ULg; Paquot, Michel ULg et al

in Food and Bioprocess Technology (2013)

Abstract This study examined the effect of the incorporation of flesh fibre concentrate (FFC) from apple, pear, and date pomaces on wheat bread dough performance and bread quality. The nutritional ... [more ▼]

Abstract This study examined the effect of the incorporation of flesh fibre concentrate (FFC) from apple, pear, and date pomaces on wheat bread dough performance and bread quality. The nutritional composition and techno-functional properties (water-holding capacity, oil-holding capacity, swelling capacity) of FFC were determined beforehand. Dough performance was evaluated by farinograph, alveograph and visco-amylograph. Bread quality was assessed by physical (weight, specific volume, and color) and textural (hardness and elasticity) parameters. Digital imaging analysis was also performed in order to better understand the observed effects. Results showed that the addition of FFC in wheat flour significantly improved (P<0.05) dough properties inducing an increase of water absorption (from 55 to 60 %), of stability (from 4 to 31 min),of tenacity (from 83 to 116 mmH2O) , a reduction of extensibility (from 69 to 29 mm), of softening (from 60 to 20 BU), of breakdown (from 34 to 25 BU) and of setback (from 103 to 93 BU) in comparison to the control dough (without fibre). The formulation containing FFC produced loaves that had various colors (crust, 0<ΔE*<10 and crumb, 0<ΔE*<20;ΔE* corresponding to color variation), a comparable specific volume (2.7 vs 2.9 cm3/g for control) and a more aerated internal crumb structure compared to the control. During storage of breads at 20 °C, there was no significant difference [less ▲]

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See detailOsmotic dehydration of pomegranate seeds (PUNICA GRANATUM L.)
Bchir, Brahim ULg; Besbes, Souhail; Attia, Hamadi et al

Poster (2013, May 30)

Osmotic dehydration of pomegranate seeds was carried out at different temperatures (30, 40, 50°C) in a 55°Brix solution of sucrose, glucose, and mixture sucrose & glucose (50:50 wt/wt). The most ... [more ▼]

Osmotic dehydration of pomegranate seeds was carried out at different temperatures (30, 40, 50°C) in a 55°Brix solution of sucrose, glucose, and mixture sucrose & glucose (50:50 wt/wt). The most significant changes of water loss and solids gain took place during the first 20 min of dewatering. During this period, seeds water loss was estimated to 46% in sucrose, 37% in glucose and 41% in mix glucose/sucrose solution. The increase of temperature favoured the increase of water loss, weight reduction, solids gain and effective diffusivity. Differential scanning calorimetry data provided complementary information on the mobility changes of water and solute in osmodehydrated pomegranate seeds. The ratio between % frozen water and % unfreezable water decreased from 5 to 0.5 during the process. That involving the presence of very tightly bound water to the sample, which is very difficult to eliminate with this process. It also appeared that glass transition temperature depends on the types of sugar. [less ▲]

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See detailMacroporous polyhipes from CO2-in-water emulsion templates stabilized by new sugar-based surfactants
Boyère, Cédric ULg; Favrelle, Audrey; Léonard, Alexandre F. et al

Poster (2013, May 16)

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See detailSurface activity of a fluorinated carbohydrate ester in water/carbon dioxide emulsions
Favrelle, Audrey; Boyère, Cédric ULg; Tran, Kien My et al

in Journal of Colloid & Interface Science (2013), 398

The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of ... [more ▼]

The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of sodium-bis(2-ethylhexyl)sulfosuccinate (AOT). The reduction of the W/CO2 interfacial tension was measured using a pendant drop tensiometer equipped with a cell view pressurized with CO2 at 80 bar and 45 °C. It was found that the interface stabilization improved in the order AOT < 6-O-myristoyl mannose < 6-O-(2H,2H,3H,3H-perfluoroundecanoyl)-D-mannose. In the latter case, a drastic reduction of the W/CO2 interfacial tension was observed (85% reduction, interfacial tension at the equilibrium = 3.6 mN/m), which emphasizes the advantage of using a fluorinated CO2-philic tail and the potential of sugars as hydrophilic head. The formulation of stable W/CO2 emulsions was also achieved using the fluorinated mannose derivative. This study paves the way to the design of a novel class of competitive surface active agents for W/CO2 emulsions. [less ▲]

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See detailAmphiphilic structure-surface property relationships of monosaccharide-based surfactants
Razafindralambo, Hary ULg; Nicks, Francois ULg; Richard, Gaetan ULg et al

Poster (2013, April 08)

A set of monosaccharide-based renewable surfactants has been prepared, structurally checked, and systematically screened for different activities and functionalities. These compounds vary in the polar ... [more ▼]

A set of monosaccharide-based renewable surfactants has been prepared, structurally checked, and systematically screened for different activities and functionalities. These compounds vary in the polar head group, linker, and hydrophobic tail. Beyond the goal to find out the most potential valuable surfactants for each measurement, relationships between chemical structure, basic properties, and functionalities have been examined by comparing compounds differing in a single structural variable. In this paper, we show and explain the impact of the anomeric alpha or bêta, neutral or acid sugar derivatives, equatorial or axial position of hydroxyl group, alkyl chain substitute attachment position, number, and length on surface properties of sugar-based surfactants. [less ▲]

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See detailComparative biochemical analysis during the anaerobic digestion of lignocellulosic biomass from six morphological parts of Williams Cavendish banana (Triploid Musa AAA group) plants
Kamdem, Irenee ULg; Hiligsmann, Serge ULg; Vanderghem, Caroline ULg et al

in World Journal of Microbiology & Biotechnology (2013)

We studied banana lignocellulosic biomass (BALICEBIOM) that is abandoned after fruit harvesting, and assessed its biochemical methane potential, because of its potential as an energy source. We monitored ... [more ▼]

We studied banana lignocellulosic biomass (BALICEBIOM) that is abandoned after fruit harvesting, and assessed its biochemical methane potential, because of its potential as an energy source. We monitored biogas production from six morphological parts (MPs) of the "Williams Cavendish" banana cultivar using a modified operating procedure (KOP) using KOH. Volatile fatty acid (VFA) production was measured using high performance liquid chromatography. The bulbs, leaf sheaths, petioles-midribs, leaf blades, rachis stems, and floral stalks gave total biogas production of 256, 205, 198, 126, 253, and 221 ml g-1 dry matter, respectively, and total biomethane production of 150, 141, 127, 98, 162, and 144 ml g-1, respectively. The biogas production rates and yields depended on the biochemical composition of the BALICEBIOM and the ability of anaerobic microbes to access fermentable substrates. There were no significant differences between the biogas analysis results produced using KOP and gas chromatography. Acetate was the major VFA in all the MP sample culture media. The bioconversion yields for each MP were below 50 %, showing that these substrates were not fully biodegraded after 188 days. The estimated electricity that could be produced from biogas combustion after fermenting all of the BALICEBIOM produced annually by the Cameroon Development Corporation-Del Monte plantations for 188 days is approximately 10.5 × 106 kW h (which would be worth 0.80-1.58 million euros in the current market). This bioenergy could serve the requirements of about 42,000 people in the region, although CH4 productivity could be improved. © 2013 Springer Science+Business Media Dordrecht. [less ▲]

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