CHAPTER X. 

 BACTERIA IN THE CHEESE INDUSTRY. 



154. Relation of bacteria to cheese. The processes 

 of cheese-making are much more affected by the operation 

 of bacterial causes than almost any other dairy industry. 

 Cheese contains so large a proportion of nitrogenous 

 matter that, so far as food is concerned, bacteria find bet- 

 ter conditions for development than in butter. The 

 ripening or curing of cheese is a fermentative process in 

 which bacteria are intimately concerned. Our knowledge 

 of the actual changes induced by these organisms is, as 

 yet, quite meager, but enough has already been deter- 

 mined to indicate that the whole industry is based largely 

 on phenomena of ferment action, and that the application 

 of bacteriological principles and ideas to this phase of 

 dairying is sure to yield more than ordinary results, in 

 explaining in a rational way, the reasons underlying many 

 of the operations of this industry. 



155. Principles of cheese-making*. The general 

 principle of cheese-making is to precipitate the casein, 

 and then press this into a more or less solid mass," allow- 

 ing it to stand for varying periods of time, and under 

 various conditions, so that a wide range is presented, in 

 which various fermentative actions may operate to pro- 

 duce the widely different kinds of cheese. From the 

 same kind of milk, a great variety of different cheeses 

 can be prepared, depending upon the treatment of the 

 milk during the manufacture, and the way in which the 



cheese is handled after it is made. 



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