556 MANUAL OF MILK PRODUCTS 



in the common infantile intestinal troubles other than the one 

 producing dysentery, it seems that high bacterial numbers in 

 the milk consumed are associated with such diseases. 



In the third place, pasteurization is of value from a com- 

 mercial standpoint in so far as it increases the keeping quality 

 of the milk and prevents financial losses caused by souring. 

 Commercial pasteurization as practiced at the present time 

 with reasonable care destroys about 99 per cent of the bacteria, 

 but it does not prevent the ultimate souring of milk, although 

 it does delay the process. 

 Quality of the milk to be pasteurized. 



Only clean milk should be pasteurized, and it should never 

 be pasteurized more than once. Dirty milk containing many 

 millions of bacteria to a cubic centimeter is not fit for con- 

 sumption, and should be condemned. Pasteurization should 

 not be resorted to in order to make dirty milk sweet long enough 

 to be sold or simply to pass legal regulations, but should be 

 used only to make clean milk a safe milk. 



Milk to be considered clean should be produced in barns free 

 from manure and floating dust. The cows should be curried 

 every day, and their flanks and udders wiped with a damp cloth 

 just before milking. The milkers should wear clean suits, and 

 their hands should be clean and dry. All milking utensils 

 should be cleaned and partly sterilized by steam or boiling 

 water. After milking the milk should be removed at once to 

 a milk house to be cooled, and it should be kept cool during 

 delivery. A farm producing milk under the above conditions 

 would score at least 70 points according to the score-card of 

 the Dairy Division. 

 Methods of pasteurization. 



Milk is pasteurized by two processes, one known as the 

 "flash" or "continuous" process, in which the flowing milk is 

 heated to the required temperature and held there from thirty 

 seconds to one minute. The other is known as the "holder" 



