References of "Razafindralambo, Hary"
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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 detailScreening of basic properties of amphiphilic molecular structures for colloidal system formation and stability: case of carbohydrate-based surfactants
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Paquot, Michel ULg

Conference (2010, March 21)

Carbohydrate-based surfactants (CBS) are amphiphilic molecules with particular interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product ... [more ▼]

Carbohydrate-based surfactants (CBS) are amphiphilic molecules with particular interests. These surface-active compounds can be produced from the most abundant renewable materials allowing large product concept possibilities. They may occur in a wide range thanks to numerous functional groups. These make possible the design of a quasi-unlimited compounds by (bio)-synthesis of new structures, or by modifying existing natural molecules. This structural diversity can generate a wide range of properties which could be developed in food and non-food applications. Our challenge is to find out the most suitable molecular structures for post)development of CBS according to the specific required properties in various industrial applications. This consists of assessing the interfacial properties of various CBS prepared by chemical, enzymatic, or chemo-enzymatic synthesis routes from the derivatives of bio-renewable materials.The effect of the polar head group, the hydrophobic chains (length, number), and the linker will be presented and discussed. [less ▲]

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See detailThermodynamic Studies Of The Binding Interactions Of Surfactin Analogues To Lipid Vesicles Application Of Isothermal Titration Calorimetry
Razafindralambo, Hary ULg; Dufour, Samuel; Paquot, Michel ULg et al

in Journal of Thermal Analysis and Calorimetry (2009), 95(3), 817-821

Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different ionic charge (z= –2 and –3) and lipid chain length (n=14 and 18) to 1 ... [more ▼]

Isothermal titration calorimetry was applied for studying the binding interactions of cyclic and linear surfactins with different ionic charge (z= –2 and –3) and lipid chain length (n=14 and 18) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidyl-choline (POPC) vesicles in 10mM Tris buffer at pH 8.5 with 150mM NaCl at 25°C. Surfactin analogues interacted spontaneously with POPC vesicles. The binding reactions were endothermic and entropy-driven process. Moreover, significant differences in the binding constant values (K) ranging from 6.6 *10^3 to 9.6* 10^4 M–1 show that cyclic structure and the increase of lipid chain length are favourable on the surfactin binding affinity to POPC vesicles, whereas the rise of the number of negative charges has an opposite effect. [less ▲]

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See detailSynthèse et propriétés tensioactives de nouveaux surfactants provenant de matières premières renouvelables.
Laurent, Pascal ULg; Razafindralambo, Hary ULg; Wathelet, Bernard ULg et al

Poster (2009)

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source ... [more ▼]

A l'heure actuelle, le bioraffinage se présente de plus en plus comme une alternative prometteuse aux filières pétrochimiques puisqu'il vise à la fois le remplacement d'une partie du pétrole comme source d'énergie et le développement de produits chimiques issus de la biomasse (végétale principalement) tels que détergents, produits phytopharmaceutiques, dissolvants, matières plastiques, etc. La valorisation de carbohydrates provenant de matières premières renouvelables fait ainsi actuellement l'objet de nombreuses recherches. Dans ce cadre, la synthèse de nouveaux tensioactifs non ioniques dérivés des acides Dglucuronique et D-galacturonique a été effectuée. [less ▲]

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See detailHigh-throughput methodology applied to screening of carbohydrate-based surfactant interfacial properties for colloidal system formulations
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Deroanne et al

Poster (2009)

Carbohydrate-based surfactants (CBS) constitute an attractive class of amphiphilic molecules owing to their structural diversity generating a wide range of properties which could be developed in food and ... [more ▼]

Carbohydrate-based surfactants (CBS) constitute an attractive class of amphiphilic molecules owing to their structural diversity generating a wide range of properties which could be developed in food and non-food applications. Based on many functional groups of the carbohydrate part, it is possible to design multiple amphiphilic structures of CBS varying in the hydrophilic head groups (mono-, oligo-, or polysaccharides), hydrophobic tail (mono-, di-, tricatenar) but also in the linker/spacer between them. The main structures of CBS include mono- and bicatenar glycolipids, bolaforms, and gemini. Moreover, CBS compounds can be produced from the most abundant renewable materials allowing large product concept possibilities. Among general properties of surfactants, interfacial properties molecules occupy a fundamental key role for colloidal system formulations since they control most of technological aptitudes required for forming and stabilizing food, cosmetic, agrochemical, detergent, and pharmaceutical products. High-throughput methodology applied to screening of CBS interfacial properties appears crucial for achieving optimum formulations of colloidal systems like foams and emulsions for which small amounts of single or mix surface-active agents are often needed and numerous physical and chemical parameters are involved. This general approach may be applied to any amphiphilic molecules produced from other renewable resources of surface-active compounds like micro-organisms and by direct extraction from vegetable materials. One of the key factors for the development of this methodology is the use of automated instrument systems in laboratory scale which are still lacking in this field compared to those existing in the analytical chemistry and biochemistry areas. [less ▲]

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See detailImpacts of the carbonyl group location of ester bond on interfacial properties of sugar-based surfactants: experimental and computational evidences
Razafindralambo, Hary ULg; Blecker, Christophe ULg; Mezdour, Samir et al

in Journal of Physical Chemistry B (2009), 113

Interfacial properties of surfactants are dependent on the conformation adopted by the hydrophilic headgroup or/and the hydrophobic tail at the boundary limit of two immiscible phases. Here, we ... [more ▼]

Interfacial properties of surfactants are dependent on the conformation adopted by the hydrophilic headgroup or/and the hydrophobic tail at the boundary limit of two immiscible phases. Here, we demonstrate the impacts of the carbonyl group (-CO-) location of the ester bond of sugar-based surfactants by comparing some properties of two closely related esters, octyl glucuronate and glucose octanoate, at the air-water interface. The carbonyl group location influences the rate and extent of interfacial adsorption and the rheology properties of sugar esters at the air-water interface, which were evaluated by dynamic surface tension and complex surface viscoelastic measurements. Octyl glucuronate adsorbs the fastest at the air-water interface whereas glucose octanoate reduces the dynamic surface tension at the lowest value and exhibits the highest film viscoelasticity. Differences are attributed to molecular conformation constraints inducing relevant changes to the surface coverage kinetic capacity and the interaction strengths of the octyl sugar ester adsorbed films at the air-water interface. All of the results are supported by the minimum cross-sectional area values per molecule determined by both experimental and computational approaches. [less ▲]

Detailed reference viewed: 155 (63 ULg)
See detailIsothermal titration calorimetry as a tool for improving enzymatic lignocellulose hydrolysis
Razafindralambo, Hary ULg; Boquel, Pascal; Jacquet, Nicolas ULg et al

Conference (2008, December)

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See detailDynamic And Equilibrium Surface Tensions Of Surfactin Aqueous Solutions
Razafindralambo, Hary ULg; Thonart, Philippe ULg; Paquot, Michel ULg

in Journal of Surfactants and Detergents (2004), 7(1), 41-46

A homologous series of surfactins containing β-hydroxy fatty acids having 13, 14, or 15 carbon atoms were isolated from the supernatant of Bacillus subtilis strain S499 cultures. Their surface-active ... [more ▼]

A homologous series of surfactins containing β-hydroxy fatty acids having 13, 14, or 15 carbon atoms were isolated from the supernatant of Bacillus subtilis strain S499 cultures. Their surface-active properties at the air-water interface were then evaluated. Dynamic surface tension data were analyzed by the relaxation function γt=γm+(γo−γm)/[1+(t/t*)n]. Based on various parameters t*, n, vmax, γm calculated from this equation, the dynamic surface properties of surfactin were found to depend on both bulk concentration and hydrophobic character of the alkyl chain. At low concentrations of surfactin, the dynamic surface tension (γd) decreased with increasing carbon atom number of the surfactin alkyl chain (n=13 to 15). However, at high concentrations, the maximum decrease of 41-4 was achieved by surfactin-C14. In contrast, more strongly hydrophobic alkyl chains in surfactins always enhanced their ability in reducing the equilibrium surface tensions and their aptitude in forming micelles. [less ▲]

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See detailRelationship between structure and biological properties of different lipopeptides produced by B. Subtilis.
Jacques, Ph.; Hbid, Ch.; Razafindralambo, Hary ULg et al

Poster (2003, August)

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See detailInteraction Of Surfactin With Membranes: A Computational Approach
Deleu, Magali ULg; Bouffioux, O.; Razafindralambo, Hary ULg et al

in Langmuir (2003), 19(8),

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See detailNouvelles fractions d'inuline. Leur préparation et leur utilisation.
Blecker, Christophe ULg; Razafindralambo, Hary ULg; Chevalier, J. P. et al

Patent (2002)

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See detail(EN) NOVEL INULIN FRACTIONS, PREPARATION AND USE
Blecker, Christophe ULg; Razafindralambo, Hary ULg; CHEVALIER, J. P. et al

Patent (2001)

The invention concerns novel inulin fractions, characterised by endothermal peaks of differential calorimetric analysis and by domains of polymerising degree, methods for obtaining said fractions by ... [more ▼]

The invention concerns novel inulin fractions, characterised by endothermal peaks of differential calorimetric analysis and by domains of polymerising degree, methods for obtaining said fractions by fractionating solutions, solutions saturated or dispersed with inulins, hydrocolloidal compositions and gels obtained with said fractions, and uses of said fractions in food composition or the like. [less ▲]

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See detailCharacterization of two Acacia gums and their fractions using a Langmuir film balance
Fauconnier, Marie-Laure ULg; Blecker, Christophe ULg; Groyne, J. et al

in Journal of Agricultural and Food Chemistry (2000), 48(7), 2709-2712

The mechanical properties of monolayers from two Acacia gums [Acacia senegal (L.) Willd. and Acacia seyal Del.] and their three fractions isolated by hydrophobic interaction chromatography were studied ... [more ▼]

The mechanical properties of monolayers from two Acacia gums [Acacia senegal (L.) Willd. and Acacia seyal Del.] and their three fractions isolated by hydrophobic interaction chromatography were studied with a Langmuir film balance to obtain a more complete understanding of their action mode. The analysis of compression isotherms revealed that A. senegal gums globally exhibit better interfacial properties than A. seyal ones. The behavior of the whole gums appeared to be strongly influenced by their arabinogalactan-protein complex. [less ▲]

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