Influence of Certain Salts, Whey Protein, and Heat Treatment Upon the pH and Rennet Curd Tension of Casein Sols

The rennet curd tension test has been used to measure the influence of added whey protein, heat treatment, and added salts upon the pH and curd firmness of 3% casein sols. Heating reduced the pH of all casein sols except sols containing high levels of sodium citrate. Addition of sodium chloride, sodium citrate, tribasic sodium phosphate, and magnesium sulfate to casein sols reduced the curd tension. Heating (62.2 or 71.1 C. for 30 rain.) increased the curd tension of 3% casein sols containing 0.18 to 0.3% sodium chloride. Heating for 30 rain. at 62.2 C. increased the curd tension of casein sols containing sodium citrate or tribasie sodium phosphate. Casein sols containing whey protein plus added salts formed clots more nearly resembling a normal clot of skimmilk, an& were found to be more heat-stable when adjusted to pH 6.50 than when adjusted to 6.10.