FROM FARM TO CONSUMER 893 



it delays decomposition, but does not entirely prevent it. 

 Cold is not the most useful preservative we have for fresh 

 organic foodstuffs, but is the least objectionable from a 

 sanitary standpoint. It has the great advantage of being a 

 natural process. Some foods when frozen may be pre- 

 served for years without veiy serious alteration. Thus the 

 flesh of the mammoth imprisoned for centuries in the 

 glacier of Siberia, when uncovered, was still found to be in 

 good enough condition to be eaten by the half-starved 

 natives. 



Milk cannot be preserved indefinitely simply by the use 

 of cold. Even at the freezing temperature some of the 

 bacteria continue to grow and multiply, and putrefaction 

 slowly takes place. Milk kept very cold does not sour, but 

 turns putrid because the lactic acid bacteria do not grow 

 at low temperatures, whereas the putrefying bacteria do. 

 Generally, milk should be kept below 50° F., which is 

 sufficient to preserve it for several days. This temperature 

 restrains the growth of most bacteria, and is a deterrent 

 especially to the harmful bacteria. Thus typhoid, diph- 

 theria, and other disease-producing micro-organisms will 

 not develop at this temperature. It would be much bet- 

 ter if milk could be kept at 45° F. instead of 50°. This 

 is the temperature requirement for certified milk. While 

 milk should be kept cold, it should not be permitted to 

 freeze, for freezing alters its composition and may render 

 it undesirable, especially for infant feeding. 



Freezing does not destroy the pathogenic bacteria. If 

 milk contains the germs of typhoid, diphtheria, scarlet 

 fever, or tuberculosis, the danger is not eliminated even if 

 the milk be frozen. Cold, therefore, while a preservative, 

 is not a germicide. The opposition to keeping milk cold 

 comes mainly from the farmer and the transportation 

 company. The farmer finds ice expensive, and the railroad 

 company complains that it is an additional burden to 

 require it to use refrigerator cars. The opposition, however. 



