CHAPTER IV 

 LACTIC STARTERS 



ACIDITY in cheese-making arises almost exclusively 

 from the lactic acid produced from the fermentation of 

 milk-sugar (lactose) by bacteria. Hydrochloric acid 

 is used in the Wisconsin l process of making pasteurized 

 milk cheese and sometimes for making skimmed-milk curd 

 for baking purposes. It is regularly used in precipitat- 

 ing casein not for food but for manufacturing purposes. 



56. Acidifying organisms. Many species of bacteria 

 have been shown to possess the power to produce lactic 

 acid by fermenting lactose. In practice, however, the 

 cheese-maker seeks to control this fermentation by the 

 actual introduction of the desired organisms and by the 

 production of conditions which will insure this dominance 

 through natural selection. For this purpose the initial 

 souring for most types of cheeses is produced by some 

 variety of the species originally described by Esten 2 

 and commonly referred to as Bacterium lactis-acidi, but 

 variously named as B. acidi-lactici, Streptococcus lacticus, 

 B. guntheri by different authors. Organisms of this 

 series dominate all other species in milk which is in- 



1 Sammis, J. L., and A. T. Bruhn, The manufacture of 

 Cheddar cheese from pasteurized milk, Wis. Exp. Sta. Research 

 Bui. 27, 1912. 



2 Esten, W. M., Bacteria in the dairy, Conn. (Storrs) Kept. 

 1896, pages 44-52. 



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