376 SCIENCE AND PRACTICE OF CHEESE-MAKING 



The following facts have some bearing on these 

 questions : 



(i) Newly made cheese has no real cheese flavor. 



(2) Some days or weeks must pass before real 

 cheese flavor begins to appear. 



(3) The breaking down of the proteins contained 

 in the cheese-curd and green cheese, resulting in the 

 formation of water-soluble protein derivatives, pre- 

 cedes, to some extent, the appearance of flavor in 

 cheese. 



(4) Cheese flavors are produced by some chemical 

 change in some compound or compounds present in 

 green cheese. 



(5) In experiments where bacterial action is pre- 

 vented, we do not find cheese flavor. 



(6) Neither galactase nor rennet nor pepsin ap- 

 pears to be able to produce compounds that have any 

 flavor at all. 



(7) Flavor develops more quickly at higher than 

 at lower temperatures. 



(8) Flavor develops more rapidly in a moist than 

 in a dry cheese. 



(9) Many of the abnormal flavors of cheese can 

 be traced directly to specific micro-organisms. For 

 example, the ofifensive odor, usually characterized as 

 "taint," is traced to a gas-producing organism closely 

 related to Bacillus coli communis, a species of bacteria 

 commonly found in the intestinal tract. 



(10) Bitter flavor in cheese has been identified 

 as a compound formed from acetaldehyd (produced 

 by the alcoholic fermentation of milk-sugar) and am- 

 monia, the product of bacterial action. 



