Heat-induced coagulation of goat milk: modification of the environment of the casein micelles by membrane processes

摘要

Unlike bovine milk, goat milk is characterised by a very low heat stability at its natural pH (i.e., 6.6-6.7). In the present work, combined membrane processes were used to evaluate how modifying the environment of the casein micelles affects the heat stability of milk. It was shown that the increase of 1.4 times of the caseins: whey proteins ratio, either through a reduction of whey proteins content or selective concentration of caseins, increased the heat coagulation temperature from 135 degreesC to 141 degreesC. Further improvement of the stability was obtained by concomitant dilution of both whey proteins and soluble low molecular weight components. From these results, we propose that the destabilising effect of whey proteins at the natural pH is linked to their ability to sensitise casein micelles to heat-induced precipitation of calcium phosphate.