The studies on the content and the change of bound water in goat's milk

Abstract

By means of the cryoscopic method with sucrosecros the authors experimented with the content and the change of the bound water in individua, goat's milk and herd milk.
Eighteen goats were used in this experiment and their breeds consisted of pure Saanens, hybrid Saanens, and Toggenburg.
The principal results obtained are summarized as follows:
1. The range of bound water content in individual milk is from 5.18% to 2.28% and the mean value of it is 3.08±0.10%. On the other hand the range and the mean value in herd milk are 4.07-2.45% and 3.19±0.19% respectively. The total mean value in both individual milk and herd milk is 3.10±0.09
2. The highest degree of freezing point in individual milk is -0.546°C and the lowest is -0.590°C The mean value of it is -0.573±0.001°C In the case of herd milk, the range and the mean value of it are -0.550°C--0.574°C and -0.564±0.001°C respectively, The total mean value in both individual and herd milk is -0.571±0.001°C.
3. The percentages of the content of the bound water with regard to some constituents of goat's milk are as follows; casein 45.31%, albumin 30.20%, fat 18.37%, and remaining solids 6.12%.
4. It is very clear that the bound water content in goat's milk decreases by the heat treatment.
The percentage of decrease is 30-10% when the milk is heated at 63°C for 30 minutes, but when the milk is heated at the boiling point for one minute, the decrease is about 50%.
5. The treatments such as heating at 63°C for 30 minutes, or boiling for one minute, have no effect on the freezing point of goat's milk.