BACTERIA IN CHEESE 237 



uniformly than when made without such a starter. Not all 

 Edam cheeses are made by the use of such a slimy whey, but 

 its use has become quite prevalent. The cheeses made from it 

 are no better than the best cheese made without it, and indeed 

 some think they are not quite so good; but they are more uni- 

 form, there is less chance for failure, and they ripen in four 

 weeks instead of six. It has been recently shown that the use 

 of a pure culture lactic starter in Edam cheese works just as 

 well as the slimy whey. 



PASTEURIZATION IN CHEESE-MAKING 



In the manufacture of hard cheeses the use of pasteurization 

 as a method of preparing the milk for the reception of a starter 

 has not been successful. Pasteurization has an effect upon milk, 

 such that it does not curdle by rennet in exactly the same way 

 that it would otherwise do. This matter is one of comparatively 

 little importance, for the curdling property can be restored by the 

 addition of a calcium chloride to the milk. But experience has 

 shown that, for some reason as yet unknown, cheeses made 

 from pasteurized milk will not ripen normally. Whether this 

 is due to the fact that pasteurization destroys certain of the 

 enzymes necessary for ripening, or to the fact that it kills some 

 of the necessary micro-organisms, or to both facts combined, is 

 not yet ascertained. Pasteurization, however, has hitherto been 

 found impracticable for the hard cheese industry. What may 

 develop in this line in the future cannot be stated. 1 



Temperature of Ripening. The ripening of hard cheeses is a 

 slow process, requiring weeks and sometimes months before 

 completion. The higher the temperature, the more rapid the 

 ripening, and the less the uniformity ~ of the cheeses. The 



1 Milchztg, p. 582, 1904. 



Henzold. Milchztg., p. 262, 1901. 



Tiemann. Milchztg., p. 386, 1901; p. 212, 1902. 



Klein and Kirsten. Milchztg., p. 6, 1901. 

 - Farrington and others. Ann. Rep. Wis. Exper. Sta., 1903. 



Babcock, Russell, Vivian and Baer. Ann. Rep. Wis. Exper. Sta., 1901. 



See also Bui. 49, Bu. An. Ind., 1903, and 20. Ann. Rep. Bu. An. Ind., 1903. 



