212 Report of the Chemical Department of the 



In normal cheese, we find an accumulation of amides and 

 annnonia, as the cheese grows older and a corresponding diminu- 

 tion of the compounds previously formed. The formation of all 

 the ammonia and of a large proportion of the amides found in 

 ripened cheese must be due to some agency other than rennet- 

 enzyme, and the only other agents present, besides milk-enzymes, 

 that can do this work appear to be organisms or their enzymes. 

 The first stage in normal cheese-ripening is essentially a peptic 

 digestion of paracasein monolactate. Gradually amides are 

 formed and later ammonia. It is probable that the first chemical 

 work done in normal cheese-ripening is the conversion of para- 

 casein monolactate by rennet-enzyme into paranuclein, caseoses 

 and peptones. The question naturally arises as to^ whether these 

 compounds must be formed before other agents can take part in 

 the work and carry it along farther, producing amides and am- 

 monia. We are at present engaged in studying this phase of 

 the problem. 



9. When rennet-enzyme was the only digesting agent in cheese, 

 we were unable in any case to find the slightest traces of cheese 

 flavor. Apparently, we must look to other sources for this im- 

 portant product of cheese-ripening. 



APPENDIX. 

 It has been considered desirable to present in greater detail 

 the data relating to the conditions of the experiments and to the 

 analytical results, in order that those who are especially inter- 

 ested in the work may have access to these details. 



CONDITIONS OF EXPERIMENTS IN CHEESE-MAKING. 



In experiments 44 to 53 and 55 to 57, rennet was used at the 

 uniform rate of 2.5 ounces for 1000 pounds of milk, and salt, when 

 added, was used at the rate of 2 pounds for 1000 pounds of milk. 

 In all experiments, the usual conditions of manufacture were fol- 

 lowed as closely as possible. Chloroform, when used, was added 

 in quantities to equal 3 to 5 per ct. of the milk by volume. The 

 cheeses were in most cases cured at 15.5° C. (60° F.). We give 

 in the following table the other details. The + sign shows that 

 a certain condition was present, while the o sign shows that the 

 condition in question was not present. 



