208 BACTERIA AND OTHER MICROORGANISMS IN CHEESE. 



water being commonly used, although vinegar is sometimes put into 

 the water. The surface is thus kept constantly moist. Because 

 of this constant moisture on the surface of the cheese, molds cannot 

 grow upon it, for they need a damp, not a wet surface ; but a quantity 

 of bacteria grow instead. These ripen the cheese, doubtless by 

 the secretion of chemical ferments, although the process has not 

 as yet been fully studied. The resulting cheese develops very 

 high flavors, closely resembling those of decay, and the cheeses 

 rapidly putrefy when they become old. If they are marketed 

 at the right stage the flavors are not strong enough to be disagreeable, 

 and many persons are very fond of them. The Limburger type 

 of cheese includes Backstein and some others. 



PRACTICAL RESULTS. 



The practical application of bacteriology to cheese-making is 

 just in its infancy, and it is quite impossible to determine the extent 

 of its development in the future. As already pointed out, cheese- 

 makers, in the last few years, have been using pure cultures of lactic 

 acid bacteria as starters to insure a more complete and more uniform 

 souring of the curd. This practice is rapidly growing. The lactic 

 starters have two purposes. First, the growth of the acid organisms 

 checks the growth of other bacteria that would be likely to spoil 

 the cheese, and this check seems to be quite necessary for the proper 

 ripening and for the preventing of faults. Second, the formation 

 of lactic acid appears to be a needed step in the chemical changes 

 that constitute the ripening. Hence, the use of a good starter of 

 acid organisms has a reasonable foundation, and we may confidently 

 assume that the practice of using starters will increase. In the 

 making of the Edam cheese of Holland, the practice of using slimy 

 whey to aid the ripening of the cheese has become very extended. 

 The slimy whey is a culture of bacteria in whey, and is, therefore, 

 simply another method of using a bacterial starter to control the 

 cheese-ripening. It hastens the ripening and makes it more uniform, 

 but it does not improve the cheese. In the manufacture of Roque- 

 fort cheese, mold cultures are intentionally added to bring about 



