CHAPTER V. 



Undesirable Fermentations 



With good management of the milk and cream, the 

 dairyman will have little to fear from undesirable fer- 

 mentations and his losses from this cause will be insig- 

 nificant. 



The rejection of milk by the creameryman on ac- 

 count of abnormality, is almost invariably the result of 

 non-observance by the producer or his helpers, of one or 

 more of the rules governing the production of clean 

 milk. 



Sour Milk 



The lactic acid fermentation or the souring of milk 

 is not, properly speaking, an undesirable fermentation; 

 it is undesirable only when the souring takes place be- 

 fore the milk has been delivered to the creamery, and is 

 one of the principal causes for rejection. On farms 

 where the milk is produced with care and cooled near to 

 50 degrees Fahrenheit, immediately after milking, and 

 shipped in due time, no untimely souring will occur, even 

 when the milk is transported a considerable distance in 

 warm weather. 



Bitter Milk 



When milk is kept at a temperature lower than 50 

 degrees Fahrenheit during a long time, the milk some- 

 times gets a bitter taste, caused by fermentation. The 

 taste is very disagreeable and makes the milk unfit for 

 use. The trouble may also be found in milk of cows 

 very far advanced in lactation, or in stripper's-milk. 



The bacteria causing the bitter taste grow at a 

 lower temperature than the lactic acid bacteria. Lactic 

 acid bacteria, under normal development, prevent the 



