lit lation of Bacteria to Cheese. 75- 



that it shall not contain injurious kinds of bacteria. As 

 will be noted later, the lactic acid bacteria are of much 

 importance in the cheese-making process. The cheese 

 maker can add these organisms in the form of a starter, 

 just as is done in butter making. The farmer should 

 furnish to the cheese maker clean milk which has been 

 kept cold so as to prevent the growth of bacteria as far as 

 possible. If this is done the cheese maker will have little 

 trouble, and the product will be good. ' In butter mak- 

 ing, fairly good butter can be made from sour cream, or 

 even cream that has an undesirable flavor if it is pasteur- 

 ized and ripened with a proper starter. The cheese 

 maker can call no such aids to his service. He can con- 

 trol in part the course of the changes that occur during 

 the making process, but after the cheese is made, he is 

 wellnigh helpless so far as the quality of the cheese is in- 

 fluenced by the milk. 



The main duty of the producer lies in the giving of 

 especial attention to the washing of the milk cans as these 

 utensils are generally employed for the return of the 

 whey to the farm. All of those factors referred to under 

 the production of clean and wholesome milk are here 

 equally applicable. 



Ripening of cheese. The rennet which is used to cur- 

 dle the milk is obtained by extracting the fourth stomach 

 of calves that have received no other food than milk. It 

 can be obtained from many other sources but not so ad- 

 vjantageously. It is prepared by the manufacturers in 

 liquid or dry form. Formerly each cheese maker pre- 

 pared his own rennet extract from the dried rennets. 

 The Swiss maker still follows this practice. The rennet 

 extract contains the enzyme, pepsin, which is found in 

 the gastric juice of all kinds of animals. This enzyme 



