References of "Razafindralambo, Hary"
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See detailInteractions between gellan gum and other polysaccharides.
Blecker, Christophe ULg; Razafindralambo, Hary ULg; Paquot, Michel ULg

in Czech Journal of Food Sciences [=CJFS] (2000), 18

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See detailMixed monolayers of gluten-emulsifiers at the air-water interface
Balla, A.; Blecker, Christophe ULg; Razafindralambo, Hary ULg et al

in Biopolymer Science: Food And Non Food Applications (1999), (91), 213-216

The interactions and miscibility analysis of gluten-emulsifiers mixed film show that those films are not completely miscible as demonstrated by the presence of both two transition zones and also by the ... [more ▼]

The interactions and miscibility analysis of gluten-emulsifiers mixed film show that those films are not completely miscible as demonstrated by the presence of both two transition zones and also by the deviation of the mean molecular areas of mixed films from the values calculated according to the rule of additivity (GAINES, 1966). Furthermore, the free energy excess of mixing is positive in presence of emulsifiers, confirming the partial miscibility of gluten emulsifier monolayers. [less ▲]

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See detailOptimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by Plackett-Burman design
Jacques, P.; Hbid, C.; Destain, Jacqueline ULg et al

in Applied Biochemistry and Biotechnology (1999), 77-9

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the ... [more ▼]

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the surfactant production. Ten active variables were analyzed by two successive Plackett-Burman designs, consisting respectively of 12 and 16 experiments to give an optimized medium. The amount of biosurfactant lipopeptides in the supernatant of a culture carried out in this optimized medium was about five times higher than that obtained in nonoptimized rich medium. The analysis of the surfactant molecules produced in such optimized conditions has revealed the presence of a third family of lipopeptides: the fengycins. The time-dependent production of these three families of molecules in bioreactors showed that surfactin S1 is produced during the exponential phase and iturin A and fengycins during the stationary phase. [less ▲]

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See detailComputer Simulation Of Surfactin Conformation At A Hydrophobic/Hydrophilic Interface
Gallet, X.; Deleu, Magali ULg; Razafindralambo, Hary ULg et al

in Langmuir (1999), 15(7), 2409-13

Using a molecular modeling method, different conformations of surfactin at a hydrophobic/hydrophilic interface are established. Two conformations of the peptide ring (S1 and S2) provided by NMR ... [more ▼]

Using a molecular modeling method, different conformations of surfactin at a hydrophobic/hydrophilic interface are established. Two conformations of the peptide ring (S1 and S2) provided by NMR experiments built with three different aliphatic chains in folded or extended configurations were studied. For the structures including the S2 peptide ring conformation, the theoretical interfacial molecular area corresponds to the experimental limiting area A0 value obtained with a Langmuir film balance. The peptide ring is positioned in the plane of the interface with the two acidic chains close to each other and protruding in the aqueous phase, and the β-hydroxy fatty acid chain, folded to interact mainly with the Leu2 side chain and also with the Val4 side chain. This design has the largest calculated molecular area and would correspond to the most stable amphipathic structure representing the surfactin experimental behavior in weak compression. [less ▲]

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See detailInterfacial and emulsifying properties of lipopeptides from Bacillus subtilis
Deleu, Magali ULg; Razafindralambo, Hary ULg; Popineau, Y. et al

in Colloids and Surfaces A : Physicochemical and Engineering Aspects (1999), 152(1-2), 3-10

The fundamental surface-active properties at the oil/water interface and emulsifying properties of surfactin, iturin A and fengycin, lipopeptides from Bacillus subtilis, were investigated. All ... [more ▼]

The fundamental surface-active properties at the oil/water interface and emulsifying properties of surfactin, iturin A and fengycin, lipopeptides from Bacillus subtilis, were investigated. All lipopeptides reduce rapidly the dynamic interfacial tension. Among lipopeptide families, surfactin is the most effective in terms of fundamental dynamic and equilibrium interfacial properties. Lipopeptides present intermediate properties in comparison with sodium dodecyl sulfate and beta-lactoglobulin concerning the stabilizing effect towards creaming-flocculation and the resistance to coalescence. Among lipopeptides, iturin A seems to show the best resistance to creaming-flocculation whereas fengycin exhibits the highest resistance to coalescence properties. (C) 1999 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMixed monolayers of gluten-emulsifiers at the air-water interface.
Balla, A.; Blecker, Christophe ULg; Razafindralambo, Hary ULg et al

Poster (1998, September)

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See detailOptimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by plackett-burman design
Jacques, Ph.; Hbid, Ch.; Razafindralambo, Hary ULg et al

Poster (1998, May)

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See detailInterfacial Properties Of Gluten Monolayers Spread On Various Chloride Salt Solutions. Effects Of Electrolytes, Salt Concentrations, And Temperature
Balla, A.; Razafindralambo, Hary ULg; Blecker, Christophe ULg et al

in Journal of Agricultural and Food Chemistry (1998), 46(9), 3535-3539

The interfacial behavior of gluten powder spread as a monolayer on aqueous phases containing various chloride salts was studied. The presence of electrolytes at low concentrations reduced the expansion ... [more ▼]

The interfacial behavior of gluten powder spread as a monolayer on aqueous phases containing various chloride salts was studied. The presence of electrolytes at low concentrations reduced the expansion and stability of the gluten monolayers compared to the results obtained with pure water. At low salt concentrations, no effect of the electrolyte nature was detectable (compression curves were superimposed for Na+, K+, and Ca2+). However, when salt concentrations increased from 0.05 to 0.5 M, the influence of the electrolyte nature on gluten film expansion appeared clearly. Divalent cations (Ca2+) gave films with greater expansion than monovalent cations (K+, Na+). Between the monovalent cations, Na+ had a greater effect on gluten film expansion than did K+. Gluten monolayer expansion evaluated by limiting the area (A0) passed through a minimum when the salt concentrations increased from 0 to 0.5 M. The temperature also influenced the behavior of gluten monolayers as attested by A0 and film elasticity values which decreased with temperature. The energy of compression (ΔGc) that measures the intermolecular forces between film-forming molecules was generally higher on Ca2+ than on K+ and Na+, showing that Ca2+ induced stronger interactions than K+ or Na+. The ΔGc − T plots showed that the compression of gluten films on various electrolytes led to ordered structures. [less ▲]

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See detailFoaming properties of lipopeptides produced by Bacillus subtilis: effect of lipid and peptide structural attributes
Razafindralambo, Hary ULg; Popineau, Yves; Deleu, Magali ULg et al

in Journal of Agricultural and Food Chemistry (1998), 46(3), 911-916

To study the effect of lipid and peptide structural attributes of Bacillus subtilis lipopeptides on their foaming properties, the formation, stability, and appearance of foams prepared with surfactins ... [more ▼]

To study the effect of lipid and peptide structural attributes of Bacillus subtilis lipopeptides on their foaming properties, the formation, stability, and appearance of foams prepared with surfactins (C13 C15) and iturins A (C14 C17) were characterized. The density and stability of lipopeptide foams depend on both the alkyl chain hydrophobic character and peptide molecular intrinsic properties. A lipidic chain length of 14 carbon atoms provides lipopeptides with the best foaming properties in terms of foam density and liquid stability in foams. Increases in alkyl chain length above 15 carbon atoms result in a drastic decrease of iturin A foam density. With the same alkyl chain, surfactin produces denser foam whereas iturin A exhibits better foaming stability. These results demonstrate the importance of the peptide structural attributes of B. subtilis on their foaming properties. [less ▲]

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See detailLipopeptides alter Bacillus subtilis hydrophobicity by adsorbing onto cell surfaces
Ahimou, François; Razafindralambo, Hary ULg; Paquot, Michel ULg

Poster (1997, October 29)

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See detailIdentification of factors influencing the production of lipopeptides by Bacillus subtilis.
Jacques, Ph.; Hbid, Ch.; Razafindralambo, Hary ULg et al

Poster (1997, April)

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See detailSurface-active properties of surfactin-iturinA mixtures produced by Bacillus subtilis
Razafindralambo, Hary ULg

Scientific conference (1997, March 16)

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See detailFoaming properties of a natural cyclic lipoheptapeptide belonging to a special class of amphiphilic molecules
Razafindralambo, Hary ULg; Paquot, Michel ULg; Baniel, A. et al

in Food Hydrocolloids (1997), 11(1), 59-62

The foaming properties of surfactin, a natural cyclic lipoheptapeptide from Bacillus subtilis, were investigated in comparison and in association with those of bovine serum albumin (BSA). An apparatus ... [more ▼]

The foaming properties of surfactin, a natural cyclic lipoheptapeptide from Bacillus subtilis, were investigated in comparison and in association with those of bovine serum albumin (BSA). An apparatus combining bubbling, optical and conductimetric methods was used to study continuously foam formation and stability in terms of the quantity and density of foam. The increase in surfactin concentration from 0.05 to 0.2 mg/ml had little effect on its foaming capacity, measured by the bubbling time to produce the required foam volume, but improved the foam maximum density significantly. Surfactin produced foam with higher maximum density and stability, and forms more regular and smaller bubbles than BSA. In addition, a synergistic effect was observed on the stability of liquid in foam prepared with a mixture of 50:50 surfactin/BSA. The liquid half-life of BSA foam was enhanced up to 40% when surfactin was added to the solution. [less ▲]

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See detailInterfacial and emulsifying properties of Bacillus suvtilis lipopeptides
Deleu, Magali ULg; Razafindralambo, Hary ULg; Popineau, Yves et al

Poster (1997)

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