9 68 Rural School Leaflet 



wear clean, white, overall milking-suits, and in almost all certified 

 dairies a clean suit is used for each milking. The milk must be bottled, 

 and it cannot be sold after it has reached a certain age. The men are 

 required to wash their hands after milking each cow. 



The primary object of certified milk is to obtain a milk that can be 

 prescribed by physicians in much the same manner as are drugs and 

 medicines. Milk is one of our best and cheapest foods and is used 

 extensively in feeding infants and invalids. Physicians have had 

 considerable difficulty in obtaining milk that was produced in a cleanly 

 manner, and this has given rise to the production of certified milk. 

 From the conditions required, one can readily see that it costs con- 

 siderably more to produce certified milk than to produce ordinary market 

 milk, and for this reason a high price is usually charged the consumer. 



Pasteurized milk is milk that has been heated to a temperature high 

 enough, and for a long enough time, to kill all pathogenic, or disease- 

 causing, germs, the milk then being cooled down to a temperature of 50° 

 or less. The main object in pasteurizing milk is to kill disease-causing 

 germs, chiefly the germs of tuberculosis. There are different temper- 

 atures and different lengths of time required for pasteurizing milk, but 

 usually, in cases when pasteurizing is required, the rule is that the milk 

 shall be heated to a temperature of 145 F. for at least twenty minutes, 

 and usually one minute in time is subtracted from the twenty minutes 

 for every degree above 145 F. to which the milk is heated. 



There are two important arguments against pasteurizing milk: in the 

 first place, frequently the work is not done thoroughly ; and in the second 

 place, the practice tends to allow the milk-producer to follow unclean 

 methods and then have these methods covered up. If, for example, 

 the cow puts her foot in the pail, many unscrupulous milk-producers 

 will not keep this milk out of the regular supply, knowing that the germs 

 entering the milk through the mishap will be killed by the process of 

 pasteurizing. However, the harmful products of these organisms would 

 still remain. Another objection to pasteurization is the fact that the 

 lactic-acid organisms which cause the souring of milk, and therefore tell 

 us when it is not fit for infants or invalids to use, are killed more readily 

 than are other organisms usually found in milk. Milk may therefore 

 appear to be perfectly wholesome and normal, and yet at the same time 

 it may contain many of the organisms that would be harmful to the human 

 system, particularly to infants and invalids. Many of the stomach 

 disorders from which infants suffer in summer might be traced to milk 

 that has been pasteurized. If, however, the milk supply is very bad 

 and it is not possible to improve it in any other way, and the process of 

 pasteurization is carried on properly, it may be a good thing. Some 

 cities require that all milk be pasteurized. 



