Bacteria and Cheese Making. 173- 



products of casein digestion, and yet be low in flavor. 

 From recent researches it seems probable that the pro- 

 duction of flavor is connected with the change that the 

 sugar undergoes in the acid fermentation, as volatile 

 acids, acetic, formic, etc., as well as alcohols and esters 

 are formed in increasing amounts as the ripening pro- 

 gresses. These may have come from the decomposition 

 of the milk sugar, or from a secondary change in the pro- 

 ducts of the lactic fermentation. There are organisms- 

 in both milk and cheese that do not grow on the ordinary 

 culture media used by the bacteriologist, and it may well 

 be that some of these are of importance in flavor produc- 

 tion. Their destruction in pasteurization is likely to be 

 one of the reasons for the failure of cheese made from 

 pasteurized milk to develop typical flavor. 



Effect of temperature on ripening. The temperature- 

 at which the ripening cheese are kept has been found to 

 be of the greatest importance *in determining the quality 

 of the product. If the cheese is kept at high temper- 

 atures, the ripening proceeds rapidly ; the cheese is short 

 lived, and has a sharp, strong flavor, and generally a 

 more or less open texture. Unless the cheese is made 

 from the best quality of milk, it is likely to undergo 

 undesirable fermentations when ripened at high tem- 

 peratures. 



Within recent years it has been found possible ta 

 ripen cheese at temperatures that were previously 

 thought to be certain to spoil the product. Much of the 

 cheese is now ripened at temperatures below 50 F. The 

 ripening goes on more slowly than at higher tempera- 

 tures, but the flavor of the cheese is clean and entirely 

 devoid of the sharp undesirable tang that is so fre- 

 quently noted in old cheese, and the texture is solid and 

 meaty. Ripening at low temperatures, when the milk is 



