CHEESE 207 



considerable surface is exposed to the air, the spoiling will 

 be more rapid than if the package is larger or if the butter 

 is hermetically scaled. 



Abnormal flavors in butter. -Various abnormal flavors 

 are noted in butter. These may be due to feed, to absorp- 

 tion of odors by the milk or cream, or to bacterial by-prod- 

 ucls. The action of the bacteria may be indirect, as in the 

 case of the "fishy" flavor in butter which is probably due 

 to the presence of small quantities of iron or copper dis- 

 solved from utensils by the acid of the cream. The small 

 amount of metal acts as a catalytic airent, accelerating to a 

 marked degree some of the decomposition changes. All 

 Is should be well tinned, so that no solvent action can 

 be exerted by the acid. 



Cheese-making. In the making of cheese it is necessary 

 for the casein and the fat to be separated from the milk 

 serum. This separation is accomplished by allowing the 

 milk to sour, or by the addition of rennet to it. The latter 

 is the method used in the making of all the varieties of 

 cheese that are of much commercial importance. Cottage 

 or sour-milk cheese is made by allowing the milk to undergo 

 an acid fermentation. It is ready for use as soon as the 

 whey has been drained from it, and represents a form of 

 fermented milk. 



The rennet cheese has no particular flavor at the time it 

 is made, and moreover is rather indigestible. It is essen- 

 tial that the green cheese be allowed to undergo a ripening 

 process in which are formed the peculiar flavors that char- 

 acterize the various types. This process also renders the 

 cheese more easily digested. Bacteria and other micro- 

 organisms function in the ripening of the different varieties 

 of cheese, which vary greatly in texture and in flavor. The 

 important commercial varieties of cheese are all made from 

 the same raw materials, cow's milk, rennet, and salt; but 



