CHAPTER IV. 

 PRESERVATION OF MILK. 



Necessity for preservative measures. It is impos- 

 sible to produce milk that does not contain bacteria. 

 Some will be present no matter how much care is ex- 

 ercised since those forms from the interior of the udder 

 <jan not be avoided. Usually many more are added to 

 the milk during the various processes of handling. If 

 the milk is left to itself, it will very soon be unfit for 

 use. It thus becomes necessary to use some means of 

 preserving the milk. This preservation may be ac- 

 complished in a number of ways: (1) by removing the 

 bacteria; (2) by preventing their growth in the milk; 

 (3) "by killing the bacteria in the milk. Most frequently 

 a combination of two or all of these methods is em- 

 ployed. 



Straining of milk. A process carried out on every 

 farm and in every cheese-factory, creamery, and milk- 

 depot is that of straining the milk. This is primarily 

 done to remove the solid particles, such as hair, straw, 

 te., that have gained entrance to the milk. These sub- 

 stances always have bacteria on their surfaces, hence 

 their removal should reduce the bacterial content of 

 the milk. The number of bacteria removed in this way 

 irj small, since the continued use of the strainer for all 

 the milk of the herd or the supply coming to the milk- 

 depot serves to wash most of the bacteria from the solid 

 particles removed by the strainer. 



