CAUSES OF RIPENING CHANGES 377 



(11) The flavoring substance, whatever it is, is 

 present in extremely small amounts 



(12) A cheesy flavor often develops in butter that 

 is not kept at sufficiently low temperature. A distinct 

 cheesy flavor is common in kumiss, when it is one o'- 

 two weeks old. 



What suggestions can we derive from the preceding- 

 statements ? 



(i) It is quite possible that the particular com- 

 pounds which furnish cheese flavor are certain pro- 

 tein derivatives that are formed only after the lapse 

 of some time and are much simpler than the principal 

 protein found in the green cheese. This suggestion is 

 supported by certain facts, (a) Cheese flavors do 

 not appear until these simpler compounds begin to 

 be formed, (b) Such compounds are known to be 

 capable of furnishing flavors, (c) Extremely minute 

 quantities of such substances go a long way in pro- 

 viding flavor. Owing to the extremely minute quan- 

 tities of such compounds present, the problem of 

 isolating and identifying them is one of great diffi- 

 culty. 



(2) We find that, in cheese cured at low tempera- 

 tures, we have, in general, about the same kinds of 

 compounds as in cheese cured at higher temperatures, 

 but the chemical changes have not gone quite so fast 

 and we have smaller quantities of these compounds 

 formed that produce flavor. This is in full agreement 

 with the characteristic mild flavor of cold-ripened 

 cheese. 



(3) In old cheese, characterized by very strong 

 flavor, especially a pungent odor and biting taste, 

 ammonia is always present in large quantities as com- 



