158 Dairy Bacteriology. 



bacteriological science, evidence was forthcoming that in- 

 dicated that it was due to the activity of organisms. 

 Schaffer 1 showed that if milk was boiled and made into 

 cheese, it failed to ripen. Adametz 2 added to greeh 

 cheese various disinfectants as creolin, thymol, etc. 

 He found that this practically stopped the curing process. 

 From these experiments, the conclusion was drawn that 

 bacteria must be the cause of the ripening. As to the 

 nature of the organisms that were supposed to be con- 

 cerned in this process, the evidence is not convincing. 



166. Digestive or peptonizing 1 theory. From the 

 chemical products determined in a matured cheese, there 

 can no longer be any question, but that the general 

 character of the cheese-ripening process is a peptoniza- 

 tion or digestion of the casein. Duclaux 3 in 1887 pro- 

 pounded the theory that this change was due to that type 

 of bacteria that are able to liquefy gelatin, peptonize 

 milk, and cause a hydrolytic change in proteids. To this 

 widely spread group that he found in cheese, he gave the 

 name tyrotlirix (cheese hairs). According to him, these 

 organisms do not function directly as ripening agents, 

 but they secrete an enzyme or unorganized ferment to 

 which he applies the name casease. This ferment acts 

 upon the casein of milk, converting it into a soluble 

 product known as caseone. These organisms grow in 

 liquid milk with great rapidity and if they function as 

 casein transformers, one would naturally expect to find 

 them at least frequently, if not predominating in the 

 ripening cheese, but such is not the case. In typical 

 cheddar cheese, however, they rapidly disappear, although 

 in the moister, softer varieties, they persist for consider- 



1 Schaffer, Milch Ztg., p. 146, 1889. 

 8 Adametz, Landw. Jahr., 18: 261. 

 3 Duclaux, Le. Lait, p. 213. 



