CHAPTER VII. 

 PASTEURIZATION OF MILK. 



ONE phase, and perhaps the most important one in the 

 sterilization of milk, has not yet been touched upon, viz., 

 that at the same time as the milk has been made to keep 

 it has also been improved from a hygienic point of view. 

 Milk is an exceptionally good nutritive medium for most 

 bacteria; we know that it has been the means, although 

 comparatively seldom, of spreading various dangerous 

 diseases, as tuberculosis, diphtheria, typhoid and scarlet 

 fever. These are all infectious diseases caused by different 

 kinds of bacteria. The bacteria thrive well in milk; 

 once there and with the person consuming the milk liable 

 to contagion, infection and disease will easily be the result. 



The pathogenic bacteria existing in milk are fortu- 

 nately all killed rapidly at a comparatively low tempera- 

 ture. Special investigations have shown that they can 

 hardly stand a heating up to 167-185 F. (75-85 C.).* 

 It is therefore not necessary to obtain complete sterility 

 in the milk to guard against infectious bacteria. 



As regards the other bacteria in milk, I want to call at- 

 tention to a point suggested by my heating experiments 

 with milk containing bacteria of different kinds. If the 

 heating was continued to about 167 F. (75 C.) it was 

 shown by subsequent bacteriological examinations that the 



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