the; care and handling of milk. 51 



The usual sources of milk contamination are dust floating 

 in the atmosphere, hairs and dust falling from the cow during 

 milking or particles of dirt and manure which often cling to the 

 flanks of the cows, dirty pails and improperly scalded utensils 

 and dirty hands and clothing of the milker. 



These fermentations exert a powerful influence upon the milk 

 and also upon the products made from it. They may be con- 

 trolled in the following ways : First, by preventing the infection, 

 which can be done by having the stable clean and the air free 

 from dust at milking time ; by wiping the cow's udder and belly 

 with a damp cloth just before milking, and keeping the flanks 

 free from manure ; by avoiding the feeding of hay or other dry 

 forage at or just before milking time ; by using properly washed 

 and thoroughly scalded utensils, having the seams well flushed 

 with solder, kept in a place secure from floating dust and washed 

 with pure water; and lastly, by the milker having clean hands 

 and clothes and being free from every contagious disease. Milk 

 drawn in this way will keep free from changes twenty 

 to twenty-four hours longer than when these precautions are not 

 taken. 



Second, by preventing the growth of germs in the milk after 

 the infection. The germs do not grow or thrive at a low tem- 

 perature and if milk is cooled quickly and thoroughly to 45 

 degrees F. or less, but little fermentation can take place and 

 milk kept in this way will remain sweet for many hours and 

 often several days longer than when the temperature is suffi- 

 ciently high to allow growth. 



At this low temperature however, after a time, a bitter or salty 

 taste may develop, due to the fact that some germs are present, 

 which develop and cause this condition at a low temperature. 



The fewer germs in the milk, the more eflFective will this 

 means of prevention be, but in all cases, it is a powerful check 

 and the principal means of controlling fermentations. 



Germs in milk may be killed by using certain chemicals known 

 as preservatives, all of which are more or less injurious to 

 human health and are prohibited by law in Maine and most other 

 states. 



They may also be killed by an application of heat. When a 

 temperature of 212 degrees F. is reached, the milk is said to be 



