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Influence de l'activité de l'eau sur les interactions lactose / [bêta]-lactoglobuline de poudres laitières modèles lyophilisées

Abstract : Model milk powders were prepared by co-lyophilization of lactose and [bêta]-lactoglobulin and stored at various water activities (aw) to better understand interactions between the two components in a dehydrated state. The presence of [bêta]-lactoglobulin influenced the critical aw where physico-chemical modifications like non-enzymatic browning, particles caking and particularly lactose crystallization, occurred. Moisture sorption isotherms, differential scanning calorimetry and X-ray diffraction demonstrated that [bêta]-lactoglobulin can both delay crystallization and increase crystallization aw to 0.54 and even 0.59 in model powders containing 10 to 30%, and 40% [bêta]-lactoglobulin respectively, compared to 0.43 for pure lactose crystallization. This stabilizing effect was due to the development ofboth covalent interactions and hydrogen bonding between lactose and [bêta]-lactoglobulin, as shown by non-enzymatic browning and spectroscopic studies. When model powders were stored at the aw just below their critical aw, preferential protein hydration occurred: hydrogen bonding between lactose and [bêta]-lactoglobulin decreased, whereas it increased between water and [bêta]-lactoglobulin. This change in hydrogen bonding seems to be responsible for the stabilizing effect against crystallization observed in model milk powders.
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Submitted on : Thursday, March 29, 2018 - 12:26:16 PM
Last modification on : Monday, April 16, 2018 - 10:42:42 AM
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  • HAL Id : tel-01749756, version 1



Marie Thomas. Influence de l'activité de l'eau sur les interactions lactose / [bêta]-lactoglobuline de poudres laitières modèles lyophilisées. Alimentation et Nutrition. Institut National Polytechnique de Lorraine, 2004. Français. ⟨NNT : 2004INPL065N⟩. ⟨tel-01749756⟩



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