References of "Wathelet, Jean-Paul"
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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 ▲]

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See detailChemical and enzymatical modifications of sugar derived from lignocellulose
Richard, Gaetan ULg; Laurent, Pascal ULg; Nott, Katherine ULg et al

Poster (2009, January)

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from ... [more ▼]

Actually, biorefinery is increasingly considered as a promising alternative to petroleum chemistry, since it aims at not only the replacement of fossil energy but also the development of chemicals from biomass, with applications such as detergents, phytopharmaceutics, solvents, plastics, etc. The valorisation of carbohydrates from renewable raw materials is currently the subject of numerous researches. In this context, the synthesis of new surfactants derived from the sugars issued from the lignocellulose hydrolysis was undertaken by chemical or enzymatic routes. In this poster, the examples of glucose, cellobiose and uronic acids will be discussed. Whatever the way used, the reaction conditions (use of a catalyst, protection/deprotection steps, type of solvent, presence of co-solvent, reactant concentrations, etc) were optimized to yield a panel of carbohydrate derivatives (some examples of the structures obtained are given above). These differ by the nature of the alkyl chain (in length and in degree of saturation), the type of chemical bond (amide, ester, thioester, acetal), and the position of substitution. The impact of these differences on the techno-functional properties of these modified sugars will be evaluated. [less ▲]

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See detailInteresterification of rapeseed oil with anhydrous milk fat and its stearin fraction. II. Modifications of melting properties
Giet, Jean-Michel ULg; Aguedo, Mario ULg; Hanon, Emilien ULg et al

in GCIRC Bulletin (2009), 25

Chemical and/or physical modification of oils and fats are commonly used by food industry to widen their range of applications (1,2). Lipase-catalysed interesterification of anhydrous milk fat (AMF) and ... [more ▼]

Chemical and/or physical modification of oils and fats are commonly used by food industry to widen their range of applications (1,2). Lipase-catalysed interesterification of anhydrous milk fat (AMF) and various vegetable oils is now a well documented procedure (3-7). The purpose of this technique is to produce original structured fats with properties different from a simple blending, that may be used as spreads or introduced into pastry. The new fats contain higher amounts of polyunsaturated fatty acids (PUFA) than butter, which provides health benefits (8,9). To our knowledge only a few authors associated AMF fractionation with blending and interesterification (10,11), although this combination may be used to increase the ratio of vegetable oil in blends and thus the PUFA content of the product. The compositional changes occurring during the lipase-catalysed interesterification of AMF/rapeseed oil (RO) and AMF stearin fraction (AMFSF)/RO blends were described in the first part of this study. In the present and second part are reported the resulting changes in physical properties, especially the melting behaviour through solid fat content (SFC), dropping point (DP) and fusion profiles by differential scanning calorimetry (DSC). [less ▲]

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See detailIntersterification of rapessed oil with anhydrous milk fat and its stearin fraction. I. Modifications of composition
Aguedo, Mario ULg; Giet, Jean-Michel ULg; Hanon, Emilien ULg et al

in GCIRC Bulletin (2009), 25

Milk fat in human diet is associated with cardiovascular diseases due to its high content in saturated fatty acids and cholesterol. Most vegetable oils are much healthier as they are rich in unsaturated ... [more ▼]

Milk fat in human diet is associated with cardiovascular diseases due to its high content in saturated fatty acids and cholesterol. Most vegetable oils are much healthier as they are rich in unsaturated fatty acids (1,2). Lipase-catalysed interesterification of oils and fats has arisen as an alternative to hydrogenation or chemical processes to produce margarine and shortenings (3), notably because they do not give rise to undesirable trans fatty acids (4). The enzyme exchanges fatty acids from one triglyceride to another, resulting in a redistribution of fatty acids species. For such a reaction, the lipase of Thermomyces lanuginosa was shown to be an efficient tool in solvent-free fat blends batches and micro-aqueous conditions (5). Enzymatic interesterification can thus be used to enrich “hard” fats with unsaturated fatty acids (6,7). As an illustration, rapeseed oil (RO) (a choice source of unsaturation-rich residues) was used in the present study to enrich anhydrous milk fat (AMF) with unsaturated C18 fatty acids (FA) (oleic, linoleic and linolenic acids). Comparatively, one “harder” fraction of AMF underwent the same reaction. The physico-chemical properties modifications induced by the reaction were followed. The compositional changes are reported in this first part and the consequent physical modifications are presented in a second part. [less ▲]

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See detailProduction of γ-Decalactone by a Psychrophilic and a Mesophilic Strain of the Yeast
Alchihab, Mohamed ULg; Destain, Jacqueline ULg; Aguedo, Mario ULg et al

in Applied Biochemistry and Biotechnology (2009), 158

Among 18 psychrophilic strains isolated near the Antarctic Station, the psychrophilic <br />strain Rhodotorula aurantiaca A19 was selected for its ability of growth and γ- <br />decalactone production at ... [more ▼]

Among 18 psychrophilic strains isolated near the Antarctic Station, the psychrophilic <br />strain Rhodotorula aurantiaca A19 was selected for its ability of growth and γ- <br />decalactone production at low temperatures. The effects of temperature, initial pH, and castor <br />oil concentration on the growth and γ-decalactone production by a psychrophilic and a <br />mesophilic strain of R. aurantiaca were investigated. The highest γ-decalactone production <br />in flasks (5.8 g/l) was obtained with the strain A19 at 14 °C and initial pH 7.0 in medium <br />containing 20 g/l castor oil. On the other hand, these factors did not affect the production of <br />γ-decalactone by the mesophilic strain. In fermentor, a γ-decalactone concentration of 6.6 g/l <br />was reached with the strain A19, whereas a maximum of 0.1 g/l was obtained with the <br />mesophilic strain. Our results suggest that the ability to synthesize γ-decalactone is a <br />particularity of the strain A19, since the mesophilic strain (no. 30645) produced small amounts, <br />and the other (no. 31354) did not exhibit this property. It is, to our knowledge, the first report of γ-decalactone production by R. aurantiaca and furthermore by a psychrophilic yeast strain. <br />Moreover, the amount of γ-decalactone obtained in fermentor with the strain 19 was on the <br />order of concentrations usually described in patents. [less ▲]

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See detailYlang-ylang (Cananga odorata (Lam.) Hook. & Thoms. var. genuina) essential oils from Comoros Islands: characterization and variability
Benini, Céline ULg; Wathelet, Jean-Paul ULg; du Jardin, Patrick ULg et al

Poster (2009)

The Union of the Comoros is the world’s biggest producer of ylang-ylang essential oils. Comorian ylang-ylang also provides the most valuable essential oil that can be found on international market. This ... [more ▼]

The Union of the Comoros is the world’s biggest producer of ylang-ylang essential oils. Comorian ylang-ylang also provides the most valuable essential oil that can be found on international market. This product represents a high percentage of Comoros’ annual currency. Ylang-ylang essential oil is obtained by fractionned hydrodistillation or steam distillation of Cananga odorata fresh flowers. This oil is commercialized in five different quality grades (extra S; extra; I; II; III) which possess their own physicochemical properties. [less ▲]

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See detailSet-up of Z- and E-guggulsterones purification method from guggul-gum extracts by liquid chromatography and study of their activities on human preadipocytes differentiation
Hanon, Emilien ULg; Keophiphath, Mayoura; Jacquemond-Collet, Ingrid et al

Poster (2009)

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and ... [more ▼]

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and cardiovascular diseases which nowadays rank among the highest causes of premature death. Therefore, modulating fat mass expansion represents a worldwide challenge. In this context, adipocyte differentiation, which corresponds to the cellular transition of a fibroblastic cell (the preadipocyte) to a highly specialized cell accumulating triglycerides (the adipocyte), is a decisive process in the expansion of adipose tissue during life span and consequently, in the development of obesity. Adipogenesis markers such as PPARg2, C/EBPa, lipoprotein lipase (LPL), perilipin (PLIN) and the adipokines (leptin and adinopectin) are known to be expressed throughout the different stages of adipocyte differentiation. Guggulsterones are the principal bioactive steroidal components found in the oleoresin (guggul gum) collected from the indian guggul tree, Commiphora mukul (Hook, ex Stocks) Engl. The objective of this study was to investigate the effects of the two purified diastereoisomeric forms of guggulsterones (Z- and E-) on the human preadipocytes proliferation and differentiation. [less ▲]

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See detailEnzymatic interesterification of anhydrous milk fat with rapeseed and/or linseed oil: oxidative stability
Giet, Jean-Michel ULg; Aguedo, Mario ULg; Danthine, Sabine ULg et al

in Journal of Agricultural and Food Chemistry (2009), 57(15), 6787-6794

Blends of anhydrous milkfat (AMF) and linseed oil (70/30), and AMF, rapeseed oil (RO) and linseed oil (LO), 70/20/10, were submitted to enzymatic interesterification. The oxidative stability of the blends ... [more ▼]

Blends of anhydrous milkfat (AMF) and linseed oil (70/30), and AMF, rapeseed oil (RO) and linseed oil (LO), 70/20/10, were submitted to enzymatic interesterification. The oxidative stability of the blends, the interesterified (IE) blends and IE blends with 50 ppm -tocopherol added as antioxidant were studied. Samples were stored in open flasks at 60°C, 25°C and 4°C, and periodically submitted to peroxide, p-anisidine, TBA value determination and UV measurement at 232 and 268 nm. The analysis of volatile compounds was carried out by SPME for the samples stored at 60°C. Peroxides appeared to be the only significant oxidation products after 12 weeks storage at 4°C. As expected, the binary blends (BB) were more sensitive to oxidation than the ternary blends (TB). The BB were associated with increased volatile emission compared to TB. Interesterification led to variable effects on the oxidation of fat mixtures, depending on composition and temperature (beneficial effect on BB, at both 25°C and 60°C, and a rather neutral effect on TB). The IE blends exhibited higher volatile release prior to ageing. A pro-oxidant effect of -tocopherol addition was observed at 25°C on both BB and TB. At 60°C, an antioxidant effect was observed on TB. [less ▲]

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See detailThe effects of purified Z- and E-guggulsterones from guggul-gum extract on human preadipocytes proliferation and differentiation through the study of gene expression of adipose markers.
Hanon, Emilien ULg; Keophiphath, Mayoura; Jacquemond-Collet, Ingrid et al

Poster (2009)

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and ... [more ▼]

The rising prevalence of obesity within both industrialized and emerging societies is a major public health problem. Indeed obesity is a usual risk factor in the development of metabolic and cardiovascular diseases which nowadays rank among the highest causes of premature death. Therefore, modulating fat mass expansion represents a worldwide challenge. In this context, adipocyte differentiation, which corresponds to the cellular transition of a fibroblastic cell (the preadipocyte) to a highly specialized cell accumulating triglycerides (the adipocyte), is a decisive process in the expansion of adipose tissue during life span and consequently, in the development of obesity. Adipogenesis markers such as PPARg2, C/EBPa, lipoprotein lipase (LPL), perilipin (PLIN) and the adipokines (leptin and adinopectin) are known to be expressed throughout the different stages of adipocyte differentiation. Guggulsterones are the principal bioactive steroidal components found in the oleoresin (guggul gum) collected from the indian guggul tree, Commiphora mukul (Hook, ex Stocks) Engl. The objective of this study was to investigate the effects of the two purified diastereoisomeric forms of guggulsterones (Z- and E-) on the human preadipocytes proliferation and differentiation. [less ▲]

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See detailThe use of Macronet resins to recover γ-decalactone produced by Rhodotorula aurantiaca from the culture broth
Alchihab, Mohamed ULg; Destain, Jacqueline ULg; Aguedo, Mario ULg et al

Poster (2009)

The objective of this study was to recover the γ-decalactone produced by R. aurantiaca from the culture broth using three Macronet resins (MN-100, MN-102 and MN-202).

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See detailProduction and toxicity of γ-decalactone and 4-hydroxydecanoic acid from Rhodotorula aurantiaca
Alchihab, Mohamed ULg; Destain, Jacqueline ULg; Aguedo, Mario ULg et al

Poster (2009)

The objective of this study was to compare the production of γ- decalactone in different scales and to study the effects of 4- hydroxydecanoic acid and γ-decalactone on the growth of R. aurantiaca. The ... [more ▼]

The objective of this study was to compare the production of γ- decalactone in different scales and to study the effects of 4- hydroxydecanoic acid and γ-decalactone on the growth of R. aurantiaca. The effect of gum tragacanth on the production of γ-decalactone by R. aurantiaca was evaluated. [less ▲]

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See detailContribution to the study of semiochemical slow release formulations. Development of flash chromatographic methods.
Heuskin, Stéphanie ULg; Farmakidis, Julien; Lorge, Stéphanie et al

Poster (2009)

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See detailGlucosinolates and their measurement
Wathelet, Jean-Paul ULg

Conference (2009)

Detailed reference viewed: 15 (4 ULg)
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See detailChemical Composition and Antioxydant Activity of Laurus nobilis Floral Buds Essential Oil
Bouzouita, N.; El Omri, A.; Kachouri, F. et al

in Journal of Essential Oil Research (2009)

The essential oil of Laurus nobilis floral buds (FB) collected in Tunisia was obtained by hydrodistillation and analysed by GC-MS. Twenty three constituents were identified. The main components of this ... [more ▼]

The essential oil of Laurus nobilis floral buds (FB) collected in Tunisia was obtained by hydrodistillation and analysed by GC-MS. Twenty three constituents were identified. The main components of this oil were α-terpinyl acetate (28.43 %), methyl eugenol (19.57 %), eugenol (7.42 %) and elemicin (4.41 %). The antioxidant activity of the oil of Laurus nobilis FB was evaluated by two methods, β-carotene bleaching (BCB) test and 2.2-diphenyl-β-picrylhydrazyl (DPPH) assay using respectively butylated hydroxytoluene (BHT), trolox, gallic acid, caffeic acid and δ-tocopherol as standards. It was found that the Laurus nobilis FB oil have a significant antioxidant effect when tested by each method respectively. The antioxidant activity of this oil is more effective than the synthetic antioxidant (BHT) at 200 ppm and can be attributed to the active compounds eugenol, elemicin and methyl eugenol present in this essential oil. [less ▲]

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See detailWheat root ecophysiology: understanding communication between wheat root system and soil microorganisms.
Delaplace, Pierre ULg; d'Ans, Séverine ULg; Wathelet, Jean-Paul ULg et al

Poster (2009)

Studies leading to a better understanding of the mechanisms involved in the communication between soil microorganisms and root system can potentially lead to improved fertility management strategies. Up ... [more ▼]

Studies leading to a better understanding of the mechanisms involved in the communication between soil microorganisms and root system can potentially lead to improved fertility management strategies. Up to now, the characterization of such interactions has been mainly focused on root exsudates but volatile organic compounds (VOC) also play a role as chemical messengers in positive interactions occurring in the rhizosphere. We aim to better understand the VOC-mediated chemical ecophysiology of soil. Wheat (Triticum aestivum L.) was chosen in this project based on its importance for food production and industrial applications. [less ▲]

Detailed reference viewed: 72 (18 ULg)