The effect of heating on physicochemical and renneting properties of milk: A comparison between caprine, ovine and bovine milk

The effect of heating at 75-90 degrees C for 30 s to 10 min on physicochemical characteristics and renneting properties of ewe's, goat's and cow's milk was studied. In the three species, the kinetics of whey protein denaturation led to the same maximum rate of denaturation corresponding to about 80% of total whey protein, whereas diffusible calcium decreased to about 20% of its initial value after the most severe heating. Micelle size increased from 25% in goat's milk to 75% in ewe's milk but remained unchanged in cow's milk. Renneting properties of goat's and ewe's milk were much less impaired by severe heating than in cow's milk. The latter lost its ability to form a gel when heating intensity was higher than 90 degrees C for 1 min, whereas in goat's and ewe's milk, coagulation was slowed down but remained always measurable. Curd whey draining capacity was severely reduced by heating, but to a lesser degree in goat's milk than in cow's and ewe's milk. (C) 1998 Elsevier Science Ltd. All rights reserved.