References of "Wathelet, Jean-Paul"
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See detailThe use of Macronet resins to recover decalactone produced by Rhodotorula aurantiaca from the culture broth
Alchihab, Mohamed ULg; Aldric, Jean-Marc ULg; Aguedo, Mario ULg et al

in Journal of Industrial Microbiology & Biotechnology (2010), 37(2), 167-172

During the biotransformation of castor oil into -decalactone, R. aurantiaca produced both the lactone form and its precursor (4-hydroxydecanoic acid). After six days of culture, a maximum yield of ... [more ▼]

During the biotransformation of castor oil into -decalactone, R. aurantiaca produced both the lactone form and its precursor (4-hydroxydecanoic acid). After six days of culture, a maximum yield of -decalactone of 6.5 g/l was obtained. The parameters of -decalactone adsorption on three Macronet resins (MN-202, MN-102 and MN-100) were investigated in water. Adsorption isotherms of -decalactone for the three Macronet resins were linear. The trapping of -decalactone produced by R. aurantiaca on these resins was then carried out. -Decalactone was eVectively retained by all the studied Macronet resins. The resin MN-202 trapped -decalactone more eYciently than MN-102 and MN-100. The percentages of -decalactone adsorbed on the resins MN-202, MN-102 and MN-100 were, respectively, 85, 75 and 81%, whereas around 70% of the adsorbed -decalactone was then desorbed. We propose an industrial process that uses Macronet resins to extract -decalactone from culture broth of R. aurantiaca. [less ▲]

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See detailValidation of a fast gas chromatographic method for the study of semiochemical slow release formulations
Rozet, Eric ULg; Heuskin, Stéphanie ULg; Lorge, Stéphanie et al

in Journal of Pharmaceutical & Biomedical Analysis (2010), 53

The validation of a fast GC-FID analytical method for the quantitative determination of semiochemical sesquiterpenes (E-β-farnesene and β-caryophyllene) to be used in an integrated pest management ... [more ▼]

The validation of a fast GC-FID analytical method for the quantitative determination of semiochemical sesquiterpenes (E-β-farnesene and β-caryophyllene) to be used in an integrated pest management approach is described. Accuracy profiles using total error as decision criteria for validation were used to verify the overall accuracy of the method results within a well defined range of concentrations and to determine the lowest limit of quantification for each analyte. Furthermore it allowed to select a very simple and reliable regression model for calibration curve for the quantification of both analytes as well as to provide measurement uncertainty without any additional experiments. Finally, this validated method was used for the quantification of semiochemicals in slow release formulations. The goal was to verify the protection efficiency of alginate gel beads formulations against oxidation and degradation of sesquiterpenes. The results showed that the alginate beads are adequate slow release devices which protect the bio-active molecules during at least twenty days. [less ▲]

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

in SciTopics / Research Summaries by Experts (2010)

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See detailEtude de la composition chimique de l'huile essentielle du lentisque de la région orientale du Maroc
Aouinti, F.; Amhamdi, H.; Wathelet, Jean-Paul ULg et al

Poster (2010)

Le lentisque ou pistachier appartient à la famille des Anacardiacées. C'est un arbuste poussant dans les sites arides de la région méditerranéenne (Asie, Europe, Afrique). On l'appelle aussi arbre à ... [more ▼]

Le lentisque ou pistachier appartient à la famille des Anacardiacées. C'est un arbuste poussant dans les sites arides de la région méditerranéenne (Asie, Europe, Afrique). On l'appelle aussi arbre à mastic car sa sève est utilisée pour la réalisation d'une gomme à odeur prononcée. Son huile essentielle est obtenue par hydrodistillation et analysée par chromatographie en phase gazeuse. L'objectif ce ce travail est l'étude de la composition chimique de l'huile essentielle du lentisque récolté de différentes zones de la région orientale du Maroc. [less ▲]

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See detailTechnique d’extraction et activité antibactérienne des huiles essentielles
Benchat, N.; Amhamdi, H.; Wathelet, Jean-Paul ULg et al

Poster (2010)

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See detailEffets du mode d’extraction des huiles essentielles sur l’efficacité de l’inhibition de la corrosion
ramdani, M.; Benchat, N.; Amhamdi, H. et al

Poster (2010)

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See detailL’extraction des huiles essentielles par micro-ondes : Quels avantages ?
Ramdani, M.; Benchat, N.; Amhamdi, H. et al

Poster (2010)

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See detailSeasonal variation in the essential oil composition of Artemisia herba alba, Growing in Eastern Morocco
Imelouane, B.; El Bachiri, A.; Wathelet, Jean-Paul ULg et al

Poster (2010)

The seasonal and even the number of hours that enable plants to be exposed to sunlight, may influence the phytochemistry of the plant since some compounds may be accumulated at a particular period to ... [more ▼]

The seasonal and even the number of hours that enable plants to be exposed to sunlight, may influence the phytochemistry of the plant since some compounds may be accumulated at a particular period to respond to environmental changes. Objectifs The seasonal variation of the essential oil extracted from the aerial parts of Artemisia herba alba growing in eastern Morocco (Taforalt) has been studied. [less ▲]

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

in Tetrahedron Letters (2010), 51

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

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

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See detailCobalt-mediated radical polymerization (CMRP) and coupling reaction (CMRC): mechanistic advances ans synthetic opportunities
Debuigne, Antoine ULg; Poli, Rinaldo; De Winter, Julien et al

Poster (2009, December 14)

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

Poster (2009, October 15)

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

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

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

Poster (2009, October 15)

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

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

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See detailRecovery of γ-decalactone produced by Rhodotorula aurantiaca from the culture broth using Macronet resins
Alchihab, Mohamed; Aldric, Jean-Marc ULg; Aguedo, Mario ULg et al

in New Biotechnology (2009, September), 25S

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

Poster (2009, July 07)

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

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

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See detailPilot scale biotransformation of vegetal oil into natural green note flavor using sugar beet leaves as sources of hydroperoxide lyase
Gigot, Cédric ULg; Ongena, Marc ULg; Fauconnier, Marie-Laure ULg et al

Poster (2009, June 02)

Natural green note aromas (GLVs) are highly attractive flavors commonly used in the food industry. These are produced in extremely low levels upon physiological stress in plant organs of any sort. This ... [more ▼]

Natural green note aromas (GLVs) are highly attractive flavors commonly used in the food industry. These are produced in extremely low levels upon physiological stress in plant organs of any sort. This weak sporadic presence entails a very expensive extraction step to obtain pure GLVs. Therefore catalytic biotransformations of fatty acid sources, the initial substrate for GLVs, have been developed. Enzymatic defense pathways and particularly the LOX pathway produce the major part of GLVs. Unlike GLV molecules that are emitted in the atmosphere, the enzymes are extractible from the plant material. Thus, a combination of plant enzyme extracts and substrate preparations provides all the ingredients for GLV production. Besides, sugar beet leaves present high levels of hydroperoxide lyase among plant sources and are available in large amounts during three months. In this enzymatic pathway, fatty acids are successively transformed by lipase, lipoxygenase and hydroperoxide lyase into aldehydes and alcohols, final compounds of GLVs pathway. Limiting and problematic steps occur with the action of hydroperoxide lyase, when enzymatic catalysis is followed by an enzyme destabilization. Alternative substrates bind irreversibly to the heme group of the enzyme and end the reaction. This poster briefly describes the development of a complete bioprocess for natural GLV production, from hydrolysis to purification. A high level of biotransformation could be achieved using optimum experimental conditions and a cheap source of plant materials. [less ▲]

Detailed reference viewed: 48 (2 ULg)