A method is described for the measurement of the firmness of the rennet curd from 100 ml. samples of milk coagulated under conditions simulating those of the cheesemaking process. Tests with a series of homogeneous curds ranging in firmness from very soft to very hard showed that the curds behaved as elastic gels of varying modulus, and the deformation produced under a suitable compressive load was accordingly adopted as a simple objective measure of firmness.

The method was used to observe the variation in the curd firmness of samples of milk from individual cows and separate quarters, with some observations on the relationship between curd firmness and milk composition, and the effect on curd firmness of variations in the following factors: acidity, addition of calcium chloride, amount of rennet, time of coagulation, and the admixture of soft-curd milk.

The results of these experiments indicate that the method provides a satisfactory measure of the rennet curd firmness of small samples of milk. The utility and applications of the method are discussed, and the suggestion is made that a standardized reproducible test on the same principle should be evolved to serve the same function with regard to milk for cheese making as the standardized measurement of curd tension serves with regard to the digestibility and suitability of milk for infant feeding.