CHAPTER VIII. 



BACTERIA IN CHEESE-MAKING. 



IN cheese-making, microorganisms are of even more sig- 

 nificance than in the manufacture of butter. Butter made 

 from unripened cream will command a market, though a 

 small one, while unripened cheese commands no market at 

 all. The changes which take place in the cream during the 

 ripening are of considerable significance, but the changes 

 that take place in the cheese during its much longer period 

 of ripening are more profound and result in producing in 

 the ripened cheese a series of chemical compounds not present 

 in the original unripened product. The market value of 

 cheese is dependent upon its ripening. 



In the manufacture of cheese some means is adopted for 

 precipitating the casein of the milk. This is commonly done 

 by the addition of rennet, although certain forms of cheese, 

 known as sour milk cheeses, are made of milk that is simply 

 allowed to sour and curdle, after which the curd can readily 

 be separated from the liquids and made into cheese. The 

 completeness with which the liquids are removed from the 

 curd differs greatly in different types of cheese, and one of 

 the large factors which determine the character of the cheese 

 is the amount of liquid which is allowed to remain in the 

 curd. After the curd is separated from the liquid it is molded 

 into various shapes and .then allowed to undergo ripening, 

 a process which results in the final market product. 



Soft Cheeses. There are two quite different types of 

 cheese, depending upon the amount of liquid left in the curd. 

 The first includes the soft cheeses, such as the Limburger, the 

 Camembert (Fig. 24, 9), the Brie cheeses (Fig. 27, 6), etc. 



