New York Agricultural Experiment Station. 205 

 Table VI. — Showing'Composition of Cheese made from Pasteurized Milk. 



In studying these results, we notice: 



(1) There was an increase in all the different classes of water- 

 soluble compounds during the 9 months of ripening. 



(2) The amount of amido compounds was considerably in 

 excess of the amounts found in cheese made with chloroform. 



(3) Ammonia was formed in 52 and 53, while none was present 

 in experiments 44 to 51. 



(4) The increased amount of amido compounds and of 

 ammonia observed in experiments 52 and 53, as compared with 

 experiments 44 to 51, must be ascribed to the presence in the 

 former of an active biological factor. 



THE destruction OF MILK-ENZYMES BY HEAT. 



In our experiments in using pasteurized milk for studying the 

 proteolytic action of rennet-enzyme in cheese and milk, we have 

 stated that no enzyme was present in the milk when made into 

 cheese except that added in the rennet-extract. It is well known 

 that milk contains a proteolytic enzyme, as shown first by Bab- 

 cock and Russell and confirmed by our own' work and that of 

 others. In studying the action of rennet-enzyme, it is essential 

 that all other enzymes previously existing in the milk shall be 

 rendered inactive. It is commonly held that these enzymes are 

 destroyed at 85° C. (185° F.). After pasteurizing the milk used 

 in our various experiments, we took the precaution to keep 

 samples of the milk for examination. These samples were treated 

 with 3.5 per ct. of chloroform by volume and determinations of 

 the soluble nitrogen compounds were made at intervals. The 

 results of this work are given in the accompanying table. 



