488 MICROBIOLOGY OF MILK AND MILK PRODUCTS 



The butter-maker can control, through pasteurization and the use 

 of pure lactic cultures, the fermentation of the cream. The pasteuri- 

 zation may be so efficient as to destroy all non-spore-forming bacteria 

 since the quality of the product will not be impaired by the use of 

 temperatures approximating the boiling point. The cheese-maker 





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FIG. 146. The type of curd obtained from milk in which the acid-forming flora 

 consi ts largely of organisms of the B. coli-aero genes group. Many gas holes and 

 few irregular shaped, angular, mechanical holes due to imperfect "matting." 

 (Original.) 



is much more dependent on the original quality of the milk, since it 

 has not been found possible to make most of the important varieties of 

 cheeses from pasteurized milk. If undesirable forms of microorganisms 

 are present in the milk, they will pass into the cheese and there produce 

 their harmful effects. Through the addition of pure cultures of 



