150 Dairy Bacteriology. 



the moisture which is separated from the curd in the 

 whey. If a rather dry, slow- curing cheese is wanted, 

 the curds are cooked in the whey at a higher tempera- 

 ture, and for a longer time, than if a more rapidly cur- 

 ing product is desired. 



The bacteria originally present in the milk are able to 

 grow with very great rapidity under these conditions, 

 and the result is, that if the normal milk bacteria (lactic 

 acid forms) are present, there will be a steady develop- 

 ment of the acid produced by the decomposition of the 

 milk-sugar. This development of the acid in the curd 

 has a marked effect upon the character of the green 

 cheese. 



157. Influence of bacteria in making" cheese. In- 

 asmuch as the proper development of acid in the milk 

 before and after the casein is precipitated is determined 

 largely by the kind of bacteria that may happen to be 

 present, it necessarily follows that the success of the pro- 

 cess is governed somewhat by the original condition of 

 the milk as to its bacterial life. In pure, clean milk, the 

 native species of bacteria seem to be present in sufficient 

 numbers, so that the proper development of the acid in 

 the vat is rendered possible, but it not infrequently hap- 

 pens that the milk may be "off' 7 in flavor, i. e., the nor- 

 mal milk organisms may be supplanted by other species 

 of a less desirable character that have gained access to 

 the milk through improper handling. There is consider- 

 able competition among different species of bacteria when 

 growing in same fluid, and sometimes they antagonize 

 each other so strongly by reason of the by-products which 

 are formed that where one kind is in abundance, other 

 species are unable to grow. So, if certain kinds are in- 

 troduced, say from dirt or filth gaining access to the milk, 

 these species may repress the growth of the normal milk 



