184 SCIENCE AND PRACTICE OF CHEESE-MAKING 



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the conditions are normal, there is never enough sugar 

 converted into lactic acid to combine with all the avail- 

 able calcium in cheese and form free lactic acid; and 

 there is never left in the cheese, under normal con- 

 ditions, enough milk-sugar to form free acid. There- 

 fore, in normal cheddar cheese, we never have free 

 lactic acid. 



When a large amount of whey is left in cheese, 

 that means a corresponding amount of milk-sugar, 

 a correspondingly large amount of acid, with forma- 

 tion of increased amounts of calcium salts, resulting 

 in the production of what is known as "acid" or "sour" 

 cheese. 



(4) Another well-recognized function of milk- 

 sugar, as a result of the formation of lactic acid and 

 acid salts in milk, is the prevention of the growth 

 of other micro-organisms which are often present 

 in milk and give rise to forms of fermentation that 

 interfere seriously with the production of good 

 cheese, such as the micro-organisms that produce 

 gases, ill-smelling compounds, etc. It is known that, 

 if the acid salts and milk-sugar in cheese-curd are 

 removed, as is done in the case of the "soaked- 

 curd" process (p. 57), the resulting cheese undergoes 

 abnormal changes in ripening, forming products that 

 are putrefactive in character and which seriously im- 

 pair or destroy the value of the cheese as food. 



( 5 ) It may be found that the fermentation products 

 of milk-sugar are more intimately associated with the 

 development of cheese flavor than has been previously 

 thought. 



SALTS OF MILK 



The salts of milk appear, as already explained in 

 connection with the functions of milk-sugar, to 



