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Pressurisation of raw skim milk and of a dispersion of phosphocaseinate at 9 °C or 20 °C: effects on the distribution of minerals and proteins between colloidal and soluble phases

Published online by Cambridge University Press:  24 January 2006

Stéphanie Regnault
Affiliation:
Equipe de Biochimie et Technologie Alimentaires, UMR 1208 – Département Agro-ressources et Procédés Biologiques, Université Montpellier II (Sciences et Techniques), 34095 Montpellier Cedex 05, France
Eliane Dumay
Affiliation:
Equipe de Biochimie et Technologie Alimentaires, UMR 1208 – Département Agro-ressources et Procédés Biologiques, Université Montpellier II (Sciences et Techniques), 34095 Montpellier Cedex 05, France
Jean Claude Cheftel
Affiliation:
Equipe de Biochimie et Technologie Alimentaires, UMR 1208 – Département Agro-ressources et Procédés Biologiques, Université Montpellier II (Sciences et Techniques), 34095 Montpellier Cedex 05, France

Abstract

The effects of high pressure treatments (100–300 MPa; 15 min; 9 °C or 20 °C) on the distribution of minerals and proteins of raw skim milk (RSM) and of a dispersion of industrial phosphocaseinate (PC) were studied after separation of the micellar and soluble phases by ultracentrifugation (UCF). Whatever the temperature of high pressure treatments, the pressure-induced dissociation of the casein micelles was accompanied by calcium (Ca), phosphorus (P) and casein release from the micelles. The released Ca and P were or became bound to soluble proteins since progressive increases in Ca and P concentrations were observed in the UCF supernatants of RSM and of the PC dispersion but not in the ultrafiltrates from these UCF supernatants (free of soluble proteins). Simultaneously, αS1-, αS2-, β- and κ-caseins were progressively released from the micelles, as seen by electrophoretic analysis. The pressure-induced solubilisation of αS1- and αS2-caseins, essentially located in the core of the micelles, suggests that high pressure destabilised micelles including their internal structure.

Type
Research Article
Copyright
Proprietors of Journal of Dairy Research 2006

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