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:agents is, in any form, an adulteration; therefore they cannot 

 be legally used. Physical agents, that do not change or 

 decrease the nutritive value of the milk, may be used. But 

 the best way to keep milk sweet and fresh is to prevent 

 infection or contamination of the milk by strict and forced 

 cleanliness. Clean, raw milk is now considered the purest, 

 the most easily digested, aud the bestot ail kinds of milk. 



But if the dairy is not run on strict lines of cleanliness and 

 all diseased cows are not removed from the herd, the dairy- 

 man, the milk dealer, or the consumer may be compelled to 

 use some physical agent to destroy the germs and thus 

 preserve the milk, and many times prevent disease. Germ- 

 laden milk should be pasteurized or sterilized. 



Pasteurization of milk consists in heating the milk to 158- 

 167 degrees F. for 20 to 30 minutes ; then it should be cooled 

 as rapidly as possible ; placed upon ice and kept there until 

 used. Physicians are inclined to object to pasteurized milk, 

 because the useful ('?), digestive-aiding bacteria and the albu- 

 men ferments are destroyed. Pasteurization will not destroy 

 the spores of the injurious germs, but it will nearly always 

 kill the adult bacteria in the milk, and if the process is 

 repeated on three consecutive days it will destroy all of the 

 bacteria in the milk. 



Technically speaking. Sterilization means the complete 

 destruction of all the germs in milk. This may be accom- 

 plished by heating the milk to 212 degrees for 15 minutes at 

 or about the same time on three consecutive days ; or by 

 heating the milk, under pressure, to 260 to 300 degrees F. 

 Ordinarily, sterilization means heating the milk to 212 degrees 

 F. for 20 to 30 minutes. It will impart a burnt or cooked 

 taste to the milk, coagulate the albumen, cause the globules 

 of fat to unite, convert the soluble into insoluble lime salts, 

 destroy the useful (?) germs, and change the color of the 

 milk. Some of these changes seroiusly interfeie with the nutri- 

 tive value and digestibility of the milk. Ordinary steriliza- 

 tion will not always kill the spores of the injurious bacteria, 

 yet it will kill all of the adult germs. Sterilized and pasteur- 

 ized milk may become sour in 48 hours if it is not kept on ice. 



