149. The coagulation of milk with rennet. Some experiments with slow-renneting and soft-curd milks

Abstract

Apart from mastitis milk there appear to be two types of soft-curd milks: (1) Milks of individual cows which throughout a lactation or throughout their lives persistently give soft-curd milks. Such milks readily respond to additions of acid and appear to be due to the breed and individuality of the cow and not to any abnormality. (2) Milks of cows or herds which, though normally giving a satisfactory coagulum, suddenly become rennet-resistant for a certain period. Such milks are more difficult to deal with as in general they do not respond to additions of acid unless these additions are large. There is little evidence available to show whether the two types are regularly related, but some individual cows in a herd do produce soft curd milk of the type which is unresponsive to the addition of acid regularly throughout a season when the majority of the cows in the herd are giving normal renneting milk. In the work described above on individual cow's milk there has been no attempt to classify the milks according to the effect of acid on the coagulation, although it is now realized that such a course would have been desirable.