Fermentations of Milk. 87 



taste. The acid fermentation of milk is often called the 

 lactic acid fermentation. In reality only the fermenta- 

 tion produced by the desirable group in which lactic 



FIG. 20. DIFFERENT TYPES OF CURDS. 



On the left a solid, homogeneous curd produced by desirable 

 bacteria; on the right, the curd produced by harmful bac- 

 teria. Note the gas holes and free whey. 



acid is the most evident by-product should be thus 

 called. 



The bacteria of this group may enter the milk from 

 the dust coming from the coat of the cow. They are 



