184 Report of the Chemical Department of the 



the decomposition of compounds like arginine and tyrosine. The 

 amount of carbon dioxide orioinally present in the milk com- 

 bined with that formed in the milk from the decomposition of 

 milk-sugar before treatment with chloroform was sufficient to 

 furnish the small amount that was given off by this cheese. 



cause' OF DIFFERENCE IN BEHAVIOR OF NORMAL CHEESE AND 

 CHLOROFORMED CHEESE. 



We have seen that, in the chloroformed cheese, only an in- 

 significant amount of carbon dioxide w'as present and after 3 

 weeks practically none was found. In the normal cheese, car- 

 bon dioxide was found in relatively large ciuantities and, even 

 at the end of 32 weeks, more carbon dioxide was being formed 

 in one week than the total amount produced in the other cheese. 

 Why should there have been so marked a difference? 



The answer to this question involves a consideration of the 

 causes that produce the proteolytic changes observed in the 

 normal cheese-ripening process. The agencies sharing in this 

 work are the following, so far as our present knowledge goes: 

 (i) Some acid, (2) enzymes present in the milk before it is made 

 into cheese, chief of wdiich is galactase, (3) pepsin and pseudo- 

 pepsin, added with the rennet in the process of cheese-making 

 and (4) micro-organisms, chiefly bacteria. 



In the case of our chloroformed cheese, we had present of 

 these dilTerent agencies, acid, galactase and rennet-pepsin. These 

 agencies, under the conditions of our experiment, were unable 

 to split carbon dioxide from tyrosine with the formation of 

 oxyphenylethylamine or change arginine into those of its pro- 

 ducts that we have commonly found in cheese ripening normally. 

 As previouslv stated, this is the first instance in our knowl- 

 edge in which arginine has been found in ripening cheese and 

 we were able to find it only because we had inhibited the action 

 of living organisms. These facts suggest strongly that the active 

 cause in our normal cheese that was responsible for the deep- 

 seated proteolysis, accompanied by production of carbon droxide, 

 was a biological factor. 



