264 Report of the Chemical Department of the 



per ct. of the nitrogen was changed into the form of water-soluble 

 compounds. How can we explain this observed fact that the rate 

 of chemical change, as measured by the formation of water- 

 soluble nitrogen compounds, decreases as the age of cheese in- 

 creases? The most obvious explanation is associated with the 

 generally observed fact that in fermentation changes the products 

 of the process weaken the action of the ferment, often inhibiting 

 it altogether. In cheese we have an accumulation of fermenta- 

 tion products in the form of water-soluble nitrogen compounds 

 and apparently they serve to diminish the action of the agents 

 that cause the changes. 



In this connection, it is interesting to notice that the end- 

 products, the amides and ammonia, appear to exert a stronger 

 influence than do the other soluble nitrogen compounds in de- 

 creasing the action of the ripening agents. This is indicated by 

 the following data taken from Table I. 



Age of Cheese. 



i^n months. 



3 ' " 

 6 " 



9 

 12 " 



18 " 



Percentage of 



nitrogen in form of 



paranuclein, caseoses 



and peptones. 



13 66 

 12.71 

 12.17 

 H.63 



Percentage of 



nitrogen in the form 



of amides and 



ammonia. 



11.44 

 16.81 

 23.48 

 31.27 



33-79 

 37.00 



Monthly average rate 



of increase of 

 soluble nitrogen com- 

 pounds for 100 lbs. 

 of nitrogen in cheese. 



15 O lbs. 



6.3 " 

 2 I " 



2.4 " 

 0.4 " 

 0.4 " 



Thus, it is seen that the first-formed products of cheese-ripen- 

 ing, paranuclein, caseoses and peptones, remain fairly vmiform, 

 while the amides and ammonia continuouslv increase. 



WHY MOISTURE INFLUENCES THE CHEESE-RIPENING PROCESS. 



We have seen that an increased moisture content in cheese 

 favors more active chemical changes in the process of ripening. 

 This may be due to one or both of two efifects. First, moisture 

 in itself may favor the activity of the ripening ferments. It is 

 well known that moisture is necessary for the action of ferments 

 and that increase of moisture above a certain amount increases 

 their action. Second, the presence of increased amounts of 



