CAUSES OF RIPENING CHANGES 



365 



indicate that the action of pepsin was able to 

 account for all the changes observed in the case of 

 rennet-extract in the presence of acid. But an inter- 

 esting difference is observable in connection with the 

 results when no acid was present. We notice that, 

 in the absence of acid, there is a gradual increase of 

 soluble compounds in the case of rennet-extract from 

 9.98 to 18.00 at the end of 9 months, but no such 

 increase is seen with the commercial pepsin. This 

 difference suggests that the rennet-extract contained, 

 in addition to the peptic ferment proper, a digesting 

 enzym not contained in the commercial pepsin; this 

 enzym shows the ability to dissolve insoluble protein 

 even in the absence of acid. This observation has 

 been confirmed by the work of others. 



The effect of commercial pepsin in increasing in 

 cheese the amount of water-soluble proteins, when 



EFFECT OF COMMERCIAL PEPSIN IN CHEESE-RIPENING 



