Effect of Skimmilk Heat Treatments on Cottage Cheese Manufacture

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Abstract
Calcium chloride, anhydrous, when used at the rate of 0.02% of the skimmilk, was not beneficial in the manufacture of cottage cheese from pasteurized skimmilk, from skimmilk heated to 175[degree]F for 30 minutes, from "low-heat" nonfat dry milk (NDM), or from "bakery-type" NDM. Heat treatments of concentrated skimmilk, such as might occur in condensing or in drying, damaged the cheese-making properties of the milk after reconstitution. However, such heat treatments did not induce measurable changes in solubility of whey proteins as measured by the Harland-Ashworth method, A.D.S.A. curd tension test, or solubility index, but they did decrease the strength of casein coagulum as measured by the rennet and the rennet-calcium tests for curd strength. Cottage cheese of good commercial quality was manufactured from fluid skimmilk which had been heated to 175[degree]F for 30 minutes to denature the whey proteins; the cheese was made by using up to 20 ml rennet per 1000 lb. of skimmilk and cutting the curd at the A-C endpoint. Gains in yields of curd by increased recovery of milk solids approximated 10%. Time from adding starter to cutting was decreased. When normal making procedures were followed after cutting, the finished cottage cheese was criticized more often than the low-heat controls for slight mealiness, slight lack of uniformity of particle size, and pH that was considered to be too high for best keeping quality.