Observations on the heat-induced salt balance changes in milk II. Reversibility on cooling

Abstract

SummaryMilk which had been heated to 85°C for 40 min was examined for changes to milk salts taking place upon cooling to 4, 20, 40 and 60°C. The time-concentration curves showed a two-step reaction for Ca, Pi and pH. The effect of the heat treatment in milk heated to 85°C for 40 min was to produce greater changes in the second step of the reaction. Because of the variability of the results for other species (Mg and citrate), the reversibility was calculated only for Ca and P. It was 90–95% and 93–99% respectively depending on the cooling temperature. The reversibility of the heat-induced changes and especially of the possible dissolution equilibrium between Ca phosphate and citrate precipitates on cooling are discussed.