New York Agricultural Experiment Station. 207 



factors not found in the other experiments. So far as these re- 

 sults go, they appear to indicate that, in cheese-ripening, salt, in 

 the proportions commonly used, has little or no influence upon 

 the action of rennet-enzyme, and that the retarding action ob- 

 served in normal cheese, due to salt, comes from its influence 

 upon other proteolytic agents. The results appear to us to call 

 for additional work, before this point can be regarded as defi- 

 nitely settled. It may be mentioned in this connection thai 

 Chittenden and Allen ^ have shown that the action of pepsin in 

 digesting blood-fibrin is diminished by the presence of common 

 salt 



effect of abnormal conditions present in experiments. 



We have already called attention to the difference of conditions 

 present in the experiments described in this bulletin and those 

 found in normal cheese. We will now consider these in more 

 detail. These abnormal conditions found in our experiments, 

 but not present in normal cheese, are the following: (i) Milk 

 heated to 85° C. to 98° C. (185° F. to 208° F.) to destroy all 

 enzymes originally existing in milk; (2) the use of calcium chlo- 

 ride or carbon dioxide gas to restore the coagulating property of 

 milk-casein by rennet-extract; and (3) the use of chloroform to 

 suppress all activity of organisms. The question naturally arises 

 as to whether the introduction of these unusual conditions seri- 

 ously affected the results obtained and, if so, in what manner and 

 to what extent. 



Does the pasteurising of milk affect the proteolytic action of rennet- 

 extract in relation to cheese-ripening? — A study of the data em- 

 bodied in Tables I, II and III indicates that when the conditions 

 were favorable for the action of rennet-enzyme or pepsin, we 

 found more or less proteolysis taking place in cheese made from 

 milk that had been heated as high as 98° C. (208° F.). In ex- 

 periments 44, 47, 49 and 50, our results were negative, not be- 

 cause the milk had been heated, but because no acid was present, 

 a condition that is essential for the action of rennet-ferment. In 

 experiments 45, 46, 48 and 51, varying degrees of proteolysis 

 were found but in these experiments acid was present, the milk 



« Studies in Physiol. Chem. Yale Univ. 1 : 92 (1884-85). 



