ALCOHOLIC FERMENTATIONS OF MILK. QI 



v 



from, or how they can possibly find conditions in nature 

 which are warm enough to enable them to grow, we do not 

 know. There is no reason for thinking that they have any- 

 thing to do with the changes which occur in milk, and for 

 dairy purposes they may be neglected. Indeed, practically 

 nothing is known about them at the present time beyond the 

 curious fact of their growth at high temperatures only. 



It should finally be noticed that there are other less definite 

 troubles arising in milk which must be attributed to bacteria. 

 Dairymen sometimes speak of " tainted milk," " foul-tasting 

 milk," " turnip-tasting milk," " putrid milk," etc. Little is 

 known about the cause of such troubles. A turnip taste 

 seems to be due partly to turnips used as food, and partly to 

 bacteria (B. fcetidus lactis). Tainted milk has been traced 

 to bacteria action. These phenomena are, however, rather 

 indefinite and, though probably bacterial fermentations, exact 

 information concerning them is yet lacking. 



ALCOHOLIC FERMENTATIONS. 



If common yeast is added to a solution of cane sugar it 

 will produce an alcoholic fermentation. Indeed cane sugar, 

 if left exposed to the air, is very likely to undergo an alcoholic 

 fermentation due to the action of yeast derived from the air. 

 Milk sugar, however, does not readily undergo an alcoholic 

 fermentation, even if inoculated with yeast. It is readily 

 changed into lactic acid under the influence of bacteria, but 

 it cannot be converted into alcohol except under peculiar con- 

 ditions. It is possible to produce an alcoholic fermentation 

 in milk, but not by simply inoculating it with yeast. Under 

 these circumstances other changes take place, but the 

 alcoholic fermentation does not commonly occur. 



There are, however, several kinds of beverages known 

 which have as their foundation an alcoholic fermentation of 

 milk. These are found in different parts of the world and 



