Étude de la dynamique de l'agrégation des micelles de caséines lors de l'acidification du lait : effet de la dénaturation thermique des protéines sériques

Abstract : Understanding mechanisms of acidic milk gelation implies the knowledge of casein micelles aggregation and of the different steps leading to gel formation. Small angle static light scattering and diffusing wave spectroscopy (DWS), which is based on light scattering in turbid medium, were used in this study. Static light scattering measurements permitted to follow micelles aggregation steps in diluted media and to calculate the fractal dimension of acidic aggreptes formed. Results showed the formation of four successive particle populations. The first population corresponds to casein micelles and the others populations correspond to casein aggregates with increasing size. The fractal dimension value, determined from double logarithmic plots of intensity versus scattering wave vector (q) resulted in value around 1.8, which reflects a diffusion limited cluster aggregation mechanisms (DLCA). By static light scattering, casein/whey proteins ratio and heat treatment of milk were shown to influence the growth kinetics of aggregates, but only heat treatment of milk modified fractal dimension leading to more porous aggregates. The DWS results showed that acid gelation of unheated milk occurred via a single-stage aggregation. The aggregation pH was measured at pH 4.9 and the gelation pH was estimated at pH 4.8.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_2004_THILL-CHARDOT_V.pdf
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Submitted on : Thursday, March 29, 2018 - 12:37:14 PM
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Valérie Thill-Chardot. Étude de la dynamique de l'agrégation des micelles de caséines lors de l'acidification du lait : effet de la dénaturation thermique des protéines sériques. Alimentation et Nutrition. Institut National Polytechnique de Lorraine, 2004. Français. ⟨NNT : 2004INPL023N⟩. ⟨tel-01750074⟩

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