The Heat Coagulation of Milk: 1.—Variations in the Compositions, Heat Stability, and Other Tests of Milks from Four Cows during the Course of a Lactation Period

Abstract

Summary The relationship between the heat stability and the composition and other properties of the milks of four cows during the course of a lactation period was investigated. No marked correlation was found between the heat stability and the various tests and analyses conducted upon the milks. The rapid tests sometimes used to classify milks to be used for condensing, such as the acid test, the alcohol test, and the phosphate test, did not satisfactorily indicate the relative heat stability of the milks. The salt balance as determined by analyses of the milks showed no direct correlation with the heat stability of the samples. The buffer intensity was not related to the stability of the milks toward heat. No clear relationship was noted between the heat stabilities of the fresh milks and of their evaporated products. Each of the individual milks for the most part retained fairly constant values in many of the tests, these values being characteristic of the milk from each cow. The results of this investigation of the individual milks of four cows conclusively demonstrated the inadequacy of our present knowledge of the heat stability of milk.