i86 Report of the Chemical Department of the 



tyrosine under the conditions existing in cheddar cheese but are 

 not able to spHt these compounds into simpler ones with simul- 

 taneous formation of carboii dioxide. If this is true, then we 

 must look to some other source as the active agency in decom- 

 posing primary into secondary proteolytic cleavage products with 

 production of carbon dioxide. The only cause that can be sug- 

 gested is a biological factor. Several investigators have made 

 a study of the gases in cheese, especially in connection with the 

 formation of holes in emmenthaler cheese and the so-called 

 "huffing" common to hard cheeses; and they have without ex- 

 ception attributed the formation of gases to micro-organisms. 

 Thus, Baumann^' found the gas in cheese examined by him to 

 consist of 6^ per ct. of carbon dioxide. In this particular case 

 he assigned Bacillus diatrypticus casci as the cause. Later von 

 Klecki^^ in a similar investigation found gas produced in an 

 inoculated milk containing 31.76 per ct. of carbon dioxide and 

 he attributed its formation to Bacillus saccJiarobntyriciis. Adametz, 

 Freudenreich and Weigmann have assigned other organisms. 

 Jensen^^ suggests that the gas that causes, holes in cheese is 

 mostly carbon dioxide and that this comes from the action of 

 lactic acid bacteria upon the nitrogen compounds of the cheese. 

 While no one has probably yet solved the problem as to what 

 specific organism or organisms are responsible for the deep seated 

 chemical changes occurring in cheese, the general tendency has 

 been to look to some biological source as a prominent factor in 

 cheese-ripening. 



From the consideration of quite different dat^, we have pre- 

 viously^" arrived at the conclusion that there is a biological factor 

 at work in normal cheese-ripening. In the results presented in 

 this paper and also in the case of a large number of results not 

 yet published, we always find that in a chloroformed cheese, 

 where galactase and rennet-pepsin are the only proteolytic agents 

 present, we never have ammonia formed, while we always find 



"^"^ Landw. Versuc/ista., 42: 181 (1892). 



^^Centr.Bl.f. Bakteriol. u. Parasitenk , II Abt.. 2: 21 (1896). 

 19C>;;/r, Bl.f. Bakteriol. u. Parasitenk. ,11 Abt., 4: 217 (1898^. 

 20 N. Y. Agr. Exp. Sta. Bui. No. 203, p 244 (igoi). 



