200 BACTERIA AND OTHER MICROORGANISMS IN CHEESE. 



ferments which they have produced may continue their activity until 

 they finally produce the new products that give the flavor. 



One fact appears to be certain amid much that is still unsettled. 

 The lactic acid organisms certainly play an important part in the 

 process; at least in the ripening of the Cheddar cheeses and probably 

 the other hard cheeses as well. The lactic acid developed in the 

 early ripening cheese is necessary to the digestive changes that occur, 

 for the acid combines with the casein, a preliminary step in the 

 ripening. While their total action is not yet understood, it is 

 certain that they have a necessary part in the cheese-ripening. 



As a result of these facts, cheese-makers have, in recent years, 

 learned that the use of lactic acid starters is decidedly advantageous. 

 This practice enables the cheese-maker to control much more 

 accurately the ripening, and to reduce the number of failures. The 

 reason why the inoculation of a lactic starter tends to reduce the 

 failures in cheese-making can easily be understood from the facts 

 already presented. The lactic acid bacteria have the power of 

 checking the growth of other germs, and even of destroying them 

 altogether. When, therefore, the milk has a large quantity of 

 lactic bacteria developing rapidly in the curd, the other bacteria, 

 which might under different circumstances produce putrefaction, 

 are prevented from increasing. In the making of cheeses this 

 protecting action of the lactic bacteria becomes very important, 

 and is, indeed, the secret of good cheese. The cheese remains for 

 weeks, or even months, in a moist condition, and there is opportunity 

 all this time for the growth of bacteria. If a proper lactic organism 

 is present at the outset, the cheese will be protected from the various 

 putrefactive types that would otherwise surely injure it. Their 

 presence in sufficient quantity is responsible for many of the defects 

 to be noticed later. 



For these reasons, then, the cheese industry is learning the 

 prime importance of a strong lactic fermentation in milk that is to 

 be converted into cheese, and in order to bring this about it is 

 rapidly adopting the method of using starters. Cheese starters are 

 essentially identical with those used in butter-making, and they are 

 used in much the same way. Home starters are frequently made 



