References of "Blecker, Christophe"
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See detailTowards the synthesis of mannose derivatives of natural phenolic compounds
Sainvitu, Pauline ULg; Nott, Katherine ULg; Richard, Gaetan ULg et al

Poster (2010, October 14)

The aim of this project is to graft a sugar moiety onto polyfunctional natural phenolic compounds. This should enhance their water solubility. The choice of an adequate sugar such as mannose could provide ... [more ▼]

The aim of this project is to graft a sugar moiety onto polyfunctional natural phenolic compounds. This should enhance their water solubility. The choice of an adequate sugar such as mannose could provide cellular recognition. The synthesis route was first tested on cinnamyl alcohol which is structurally close to the base pattern of natural phenolic compounds. Two compounds are tested to catalyse the glycosilation between cinnamyl alcohol and D-mannose. The first one is an enzyme, the -glucosidase from almond, and the second one is a mineral acid catalyst immobilized on silica. Results show that -glucosidase is able to synthetize cinnamyl mannoside from mannose and cinnamyl alcohol. Furthermore, enzyme-catalyzed route lead to only one product and is so more specific than the chemical route where several products are observed. The obtaining of one product with a unique structure is interesting for the fundamental study of structure-function relationships (Interaction of the product with model membranes by Isothermal Titration Calorymetry and with the Langmuir Trough technique). In a future work, the reaction will be tested with more complex molecules (for example coniferyl alcohol). [less ▲]

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See detailA method for the production of prebiotic preparations containing isomaltooligosaccharides and gluconic acid.
Goffin, Dorothée ULg; Blecker, Christophe ULg; Paquot, Michel ULg

Poster (2010, October 14)

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. IMOs consists of glucose ... [more ▼]

Isomaltooligosaccharides (IMOs) are non-digestible oligosaccharides, considered as prebiotics and therefore aim to selectively feed probiotics indigenous to the human colon. IMOs consists of glucose monomers linked by at least one α-1-6, or in a lower proportion α -1-3 (nigerose family) or α -1-2 (kojibiose family) glucosidic linkages. In our case they are produced from either corn, tapioca, or rice hydrolyzed starch. The enzymatic reaction is achieved using an Aspergillus niger transglucosidase (EC 2.4.1.24). It results in a very complex mixture with molecules characterized at the same time by their DP value (from 2 to ~15), linkages types (α-1-2, 3 or 6) and the proportion and position of each type of linkage (only α -1-6 or combined types). However, the reaction only permits to reach yields between 50-75 % in IMOs. Impurities are composed of residual maltooligosaccharides (glucose with exclusively α -1-4 linkages) from the starting vegetal material and glucose released during the transglucosylation step. These digestible saccharides are deleterious for the prebiotic preparation. Therefore, these compounds must be eliminated from the medium or converted in prebiotic species. Residual maltooligosaccharides are thus specifically hydrolyzed by a thermostable α-glucosidase (EC. 3.2.1.20) in order to produce glucose as the only unwanted specie. This glucose can then be converted to gluconic acid and/or its salts using a glucose-oxidase (EC. 1.1.3.4) in combination with a catalase. Gluconic acid (C6H12O7) is a saccharide derivative which has been recognized as a prebiotic compound. It is also known for its purgative action and proved to be effective for lipid peroxidation prevention. A first option can then be chosen, leaving gluconic acid in the product in order to obtain an original prebiotic product enjoying new prebiotic potential properties due to the combination of both types of prebiotic compounds (IMO and gluconic acid). The second option is to eliminate the gluconic acid from the prebiotic mixture. This separation doesn’t present the same difficulties than for glucose as gluconic acid is charged and can therefore be separated on anion-exchange resins (Dowex AcO-). This overall process, fulfilling the principles of green chemistry and being applicable to produce organic prebiotic, is an elegant solution, from an economical, an environmental, a nutri-functional and a techno-functional point of view. Indeed, it can lead to original prebiotic preparations, with yields close to 100%, by avoiding product loss, as the digestible saccharides portion is converted to gluconic acid. Furthermore, the presence of gluconic acid can provide many functional properties to the prebiotic preparations for their incorporation in food products. [less ▲]

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See detailUtilisation du jus de datte comme milieu d’immersion pour la déshydratation osmotique des graines de grenade
Bchir, Brahim ULg; Besbes, Souhail; Karoui, Romdhane et al

Poster (2010, October 14)

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See detailCARBOHYDRATE-BASED SURFACTANTS FOR FORMING AND STABILIZING COLLOIDAL SYSTEMS AS EMULSIONS AND FOAMS
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Richel, Aurore ULg et al

in Abstracts book of 5th edition of world congress on emulsions (2010, October 12)

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable ... [more ▼]

Carbohydrate-based surfactants (CBS) constitute a class of amphiphilic molecules with particular and common interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product concept possibilities, and may occur in a large structural range with one or more hydrophilic head groups and hydrophobic chains with various linkers/spacers, thanks to numerous reactive functional groups in their basic structure. It is then possible to design a quasi-unlimited number of new compounds by (bio)-synthesis from various raw materials. This structural diversity can generate a wide range of properties, which could be developed in food and non-food applications. Our challenge is now to find out the most suitable molecular structures for the post-development of CBS, mainly for colloidal systems like emulsion, foam, and suspension. A pre-screening of the dynamic and equilibrium interfacial tensions and interfacial rheology properties of various CBS prepared by chemical, enzymatic, or chemo-enzymatic synthesis routes from the derivatives of bio-renewable substrates is carried out. Then, the characterization of emulsifying and foaming properties of pre-selected molecules is performed. These investigations are completed by the characterization of thermal properties of liquid suspensions and powders. Homologous series of two derivative compounds of glucuronic and galacturonic acids with mono- or bicatenar hydrophobic chains and different linkages (linear or cyclic ester, amide) have been chosen as CBS starting compounds. These were full characterized by spectroscopic techniques (RMN, SM, IR). The effect of the hydrophobic chain length and number, polar head group, and the linker on whole properties investigated is easily deduced. [less ▲]

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See detailChemical characteristics and oxidative stability of sesame paste, and olive oils.
Borchani, C.; Besbes, Souhail; Blecker, Christophe ULg et al

in Journal of Agricultural Science and Technology (2010), 12

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See detailPretreatment And Enzymatic Hydrolysis Of Miscanthus x giganteus: Influence Of Process Parameters
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

Poster (2010, September 21)

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and ... [more ▼]

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and hemicellulose content, it has attracted considerable attention as a possible energy crop to produce bioethanol. Pretreatment of lignocellulosic biomass is a key step to unlocking the protective structures so that the enzymatic hydrolysis of the carbohydrate fraction to monosugars can be achieved more easily and with greater yield. In this study, Miscanthus x giganteus was delignified by a chemical pre-treatment process using a mixture of formic acid/acetic acid (1). The treated material was then hydrolyzed. By means of Box-Behnken experimental design and response surface methodology we investigated the effect of cooking time (60, 120 and 180 min), formic acid/acetic acid/water concentration (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107°C) on the residual Klason lignin content and the % of digestibility. The optimal pretreatment process parameters were identified. [less ▲]

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See detailOsmotic Dehydration Kinetics of Pomegranate Seeds Using Date Juice as an Immersion Solution Base
Bchir, Brahim ULg; Besbes, Souhail; Karoui, Romdhane et al

in Food and Bioprocess Technology (2010)

Pomegranate seeds were osmodehydrated using date juice added with sucrose (final °Brix, 55) as immersion solution. The kinetics of osmotic dehydration showed that the most significant changes of mass ... [more ▼]

Pomegranate seeds were osmodehydrated using date juice added with sucrose (final °Brix, 55) as immersion solution. The kinetics of osmotic dehydration showed that the most significant changes of mass transfer took place during the first 20 min of the process, regardless of date juice <br />varieties. During this time, seed water loss and solid gain were estimated to be ∼39% and ∼6%, respectively. After 20 min of the process, the percentage of water loss and solid gain varied slightly and ranged on average close to ∼40% and ∼9%, respectively. During osmotic dehydration, there was a leaching <br />of natural solutes from seeds into the solution, which is <br />quantitatively not negligible, and might have an important <br />impact on the sensorial and nutritional value of seeds and date <br />juices. Both scanning electron microscopy and texture <br />(compression) analysis revealed that osmotic dehydration <br />process induced modifications of seed texture and cell <br />structure. Sucrose was found to be the essential element which <br />influences the texture of seed and the viscosity of date juice. <br />Additionally, natural sugar present in date juice permits <br />substituting 35% of the total quantity of sucrose added to the <br />osmotic solution. [less ▲]

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See detailMid-Infrared Spectroscopy Coupled with Chemometrics: A Tool for the Analysis of Intact Food Systems and the Exploration of Their Molecular Structure-Quality Relationships - A Review
Karoui, Ramdhane; Downey, Gerard; Blecker, Christophe ULg

in Chemical Reviews (2010), 110(10), 6144-6168

Public interest in food quality and methods of production has increased significantly in recent decades, due in part to changes in eating habits, consumer behavior, and the increased industrialization and ... [more ▼]

Public interest in food quality and methods of production has increased significantly in recent decades, due in part to changes in eating habits, consumer behavior, and the increased industrialization and globalization of food supply chains.1 Demand for high levels of quality and safety in food production obviously requires high standards in quality assurance and process control; satisfying this demand in turn requires appropriate analytical tools for food analysis both during and after production. Desirable features of such tools include speed, ease-of-use, minimal or no sample preparation, and the avoidance of sample destruction. These features are characteristic of a range of spectroscopic methods including the mid-infrared (MIR). While it is true that near-infrared (NIR) spectroscopy has achieved greater uptake by the food industry,2 reported applications of MIR in this sector have increased over the past decade or more. Foods represent significant analytical challenges. They are highly complex, variable and can be found in a number of different physical states: these include solids, dilute solutions, emulsions, foams, highly visco-elastic forms, and glassy [less ▲]

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See detailImpact of ageing and food additives on the physico-chemical properties of partially hydrolyzed and pregelatinized rice flour
Mertens, Cécile ULg; Blecker, Christophe ULg

Poster (2010, August 25)

Conservation of the quality of a food product is an essential preoccupation for industrials. Indeed, food acceptability by consummers depends of this quality. However, the latter decreases with time of ... [more ▼]

Conservation of the quality of a food product is an essential preoccupation for industrials. Indeed, food acceptability by consummers depends of this quality. However, the latter decreases with time of storage, due to complex alteration reactions. This study presents a first approach of alteration reactions in a particular range of products: drum-dried pregelatinized cereal products. While this type of product is widely used as thickeners or in infant foods, no study has ever been made on the subject. The cereal studied here is one of the most consumed by mankind: rice. We also investigated the impact of food additives (E170 & E340ii) on the ageing of such a product, because they are often used empirically in industry. [less ▲]

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See detailInfluence of steam explosion and thermal degradation of cellulose
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Poster (2010, August 20)

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have ... [more ▼]

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have already been removed by acid and alkaline treatments. The results of this study show that thermal degradation of cellulose fibres, studied by TGA, is still limited for a temperature process below 240 °C. However, derivative TGA show that thermal stability of cellulose obtained by these conditions decreases with the increase of temperature. For temperatures above 250°C, char level is higher at the end of the pyrolysis. According to the literature, the increase of the char level is correlated to an increase of the degradation product1. Determination of the degradation products in the liquor obtained after the pretreatment show an important increase of furfural and 5-hydroxymethylfurfural concentration with the temperature in agreement with the increase of the char level. These results confirm the important degradation of the cellulose fibres. [less ▲]

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See detailSteam explosion pretreatment and thermal degradation of cellulose fibers
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Conference (2010, August 20)

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See detailChemical properties of 11 date cultivars and their corresponding fibers extracts.
Borchani, C.; Besbes, Souhail; Blecker, Christophe ULg et al

in African Journal of Biotechnology (2010), 9(26), 4096-4105

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See detailPrésentation de Pierre Gagnaire, grand chef cuisinier
Blecker, Christophe ULg

Scientific conference (2010, May 18)

Detailed reference viewed: 22 (1 ULg)