New York Agricultural Experiment Station. 73 



From the above results it would seem that i cc. or more of 

 lactic acid to 25 grams of curd (or 4 per ct.) was too great an 

 amount for the existence of paracasein monolactate. 



In the flasks containing the bacteria and i gram of lactose we 

 are able to follow in sOme detail the results of the gradual forma- 

 tion of a large amount of acid. On March 10 a considerable por- 

 tion of the sugar in these flasks was yet untouched and about J of 

 the nitrogen was present as the monosalt. Two weeks later the 

 sugar had nearly disappeared and less than i-io of the nitrogen 

 remained in the salt-soluble form. By May 22 all the sugar had 

 disappeared and the amount of monolactate had fallen to a very 

 low figure where it remained August 15. 



From these two experiments it seems fair to conclude that in 

 forming the amount of monolactate ordinarily present in cheese 

 the bacteria use up an amount of sugar equal to more than 2 per 

 ct. and less than 4 per ct. of the cheese mass. 



the practical objection to too much acid. 



The formation of acid is an unavoidable and apparently a 

 necessary step in our present method of making cheddar cheese. 

 However, the amount of acid which is really needed is small and is 

 very easily exceeded to the detriment of the product. The exact 

 extent to which the development of acid is desirable varies con- 

 siderably, depending upon the temperature of curing and the 

 market for which the cheese is intended, but in general the forma- 

 tion of acid is carried to the point where there is a decided mel- 

 lowing of the curd. Whenever the formation of acid is carried 

 much beyond this point the curd rapidly becomes plastic and 

 refuses to part with the whey still contained within it. 



Put to press in this condition the sugar contained in the excess 

 of whey is broken down to acid, changing the curd from the plas- 

 tic condition into a tough, resistant mass with a distinct acid 

 odor. With this change in consistency the whey is set free 

 and runs out upon the shelves. The ripening processes of such 

 cheese are commonly retarded and the resulting flavor is bad. 



lactic-acid bacteria are numerous and active in cheese. 



It is but natural that very many of the lactic-acid bacteria 



which are present in the factory milk should pass over into the 



