Rennet Curd from Milk Plus Soy Protein Mixtures

Abstract

Rennet coagulated curds were made from mixtures of 80% raw milk and 20% soy protein solutions. Unfractionated soy protein solution and 11S soy protein-rich fraction were tested; rennet curd containing the latter had a higher yield of solids and harder texture. Effects of 0, 10, 20, and 40 mM added calcium chloride on textures of rennet curd were measured by the firmness and moisture content of curds. Added 40 mM calcium chloride decreased firmness of curd and increased moisture content. The soy proteins in 11S soy protein-rich fraction were co-coagulated with milk proteins by rennet from the milk/soy protein solution mixture. Soy proteins in the fraction added to milk precipitated in higher proportion than those of the skim milk added to the control milk. The casein curd microstructures were loosened by soy protein, and this caused excessive losses of milk fat. Soy protein also increased the water holding capacity of rennet curd. Heat denaturation of soy proteins of the 11S soy protein-rich fraction increased the proportion of soy proteins incorporated in curd but also increased the loss of fat and the water holding capacity of the coagulum. © 1979, American Dairy Science Association. All rights reserved.