Heat stability of reconstituted casein micelle dispersions: changes induced by salt addition

Abstract

The aim of the present work was to study the heat stability of reconstituted casein micelle dispersions (RCMD) after addition of various salt solution: NaCI, CaCl z , MgCl z , sodium citrate and sodium phosphate. Case in micelle stability to heat treatments (95 "C -10,20 and 30 min) was evaluated. Modifications of the pH, of the casein micelle pellet water content and of the minerai and casein distribution between aqueous and micellar phase were measured. NaCI addition decreased the RCMD pH, increased the amount of diffusible calcium and decreased the amount of supematant casein. CaCl z and MgCl z addition decreased the RCMD pH and the amount of supematant casein. Sodium citrate addition, with a solution at pH 7.4, increased the RCMD pH, drastically increased the amount of diffusible calcium, phosphorus and of supematant casein. It caused the case in micelle's destructuration. Sodium phosphate addition, with a solution at pH 7.4, did not modify the RCMD pH and increased the amount of supernatant casein. Acidification, beyond a pH value of 7.0, induced heat aggregation. Calcium and magnesium chloride addition was detrimental to casein micelle heat stability. NaCI, sodium citrate and sodium phosphate addition enhanced reconstituted casein micelle heat stability. The determinant role of the aqueous phase on reconstituted casein micelle physico-chemical properties was emphasized by this study. InraJElsevier, Paris casein micelle / salt / heat stability Rsum -Stabilit thermique de dispersions de micelles de casine reconstitues: modifications produites par l'addition de sels minraux. L'objectif du prsent travail tait d'tudier la stabilit thermique de dispersions de micelles de casine reconstitues aprs l'addition de diffrentes solutions salines: NaCI, CaCl z , MgCl z , citrate de sodium et phosphate de sodium. La stabilit au traitement thermique (95 "C, 10-20-30 min) des dispersions des micelles de casine reconstitues tait value. Les modifications du pH, de la teneur en eau des culots des dispersions de micelles de casine et de la rpartition des minraux entre phase aqueuse et micellaire taient mesures. L'addition de NaCI diminuait le pH des dispersions, augmentait la teneur en calcium diffusible et diminuait la teneur en