The Effect of Heat on the Nutritive Value of Milk Proteins as Influenced by Water and Fat

Abstract

Tests on adult dogs have shown that autoclaving non-fat dry milk solids results in a decrease in the digestibility and nutritive index of the milk proteins. In reconstituted milks, the presence of water markedly inhibits the reaction between carbohydrates and protein. The results of in vitro experiments on the heating of dried skim milk and whole milk powder reconstituted with water show an increased rate of proteolysis of the milk protein by crystalline enzymes. The fat present exerts a minimum effect. It may be concluded that the heating of milk proteins in an aqueous medium does not decrease the nutritive value of the protein constitutents; on the contrary, heat treatment under these conditions appears to enhance the rate of in vitro proteolysis.