Contrôle de la dénaturation thermique et de l'agrégation de la B-lactoglobuline en présence de co-solutés : econséquences sur les propriétés moussantes

Abstract : Heat denaturation and aggregation of -Lactoglobulin (B-LG) (80c, 10 min) in presence of cosolutes (arginine HCI, NaCI and GdnHCI) was performaed at pH 4.0 and pH 7.0. For both pH values, aggregation was induced in presence of inrasing cosolute concentrations. Physical aggregation due to change screening of positive protein surface charges with negatively charged CI was shown to be the driving factor in acidic pH conditions due to high protein stability. At pH 7.0, charged cosolutes interact with the protein helix and induce conformational modifications, leading to SH-group activation (30-35 % active SH groups) and loss of -strand structures while incrasing protein aggregation (physical aggregation and SH-SS exchange reaction). Soluble aggregates (30-80 %n 50-130 nm) are formed and insolubilisation occurs at higher cosolute concentrations. Upon charge screening the aggregation mechanism changes from RLCA to DLCA, indicated by a decrease in reaction order and stability ratio (W.). Particles with different degree of charge neutralization lead to heteroaggregation of oppositely charged particles and high reaction rates. The nature of the cosolute is of secondary importance at low cosolute concentrations, only at higher concentrations specific effects of the guanidinium group are observed. Foam stabilization properties were tested at Ph, where high amounts of aggregates were formed (>80 % vs. 30 % at Ph 4.0°. Soluble and insolulble aggreages (heated -LG/cosolute dispersions) expressed significantly lower drainage and gas diffusion rates, increased foam volume and foam liquid stability and higher amounts of small bubbles compared to -LG alone. Beside surface elasticity and viscosity the formation of a stable semi-flexible interfacial network by incorporation of soluble and/or insoluble aggregates is of importance to prevent foam coarsening
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http://docnum.univ-lorraine.fr/prive/INPL_T_2004_UNTERHASLBERGER_G.pdf
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Submitted on : Thursday, March 29, 2018 - 1:40:50 PM
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Gerlinde Unterhaslberger. Contrôle de la dénaturation thermique et de l'agrégation de la B-lactoglobuline en présence de co-solutés : econséquences sur les propriétés moussantes. Autre. Institut National Polytechnique de Lorraine, 2004. Français. ⟨NNT : 2004INPL082N⟩. ⟨tel-01752312⟩

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