322 



MILK 



Under practical conditions none of these methods of "steriliza- 

 tion" sterilize in the bacteriologic sense. A few bacteria, mostly 

 spores, remain, and, therefore, all utensils must be thoroughly 

 dried in order to prevent growth of these germs. By inverting 

 cans and pails in a warm place or in the sunshine this is readily 

 accomplished, but the air must be free from dust and other con- 

 taminating influences (Fig. 152). 



The possible sources of bacteria in utensils are chiefly rem- 

 nants of milk, air, and water. A supply of pure water must be 



Fig. 151. — Steam sterilizer for cans. 



available to avoid pollution of utensils from this source, and by 

 inverting cans the amount of dust that enters is largely reduced. 

 The milking pails should be covered with cloth after cleaning, 

 according to Harding, Ruehle, Wilson, and Smith. The authors 

 tested milk from improved Loy pails which had been cleaned in 

 the same manner and steamed for fifteen minutes, but two were 

 protected by cloths tied over the tops, while two were not so 

 treated. The pails were brought to the milkers immediately be- 

 fore milking and the cloths removed at this time. The milk in 

 the protected pails contained 922 bacteria per cubic centimeter. 



