150 Dairy Bacteriology. 



found the efficiency of the machine not wholly satisfactory 

 at the lower temperatures. At 158 F. the average of four- 

 teen tests gave 15,300 bacteria per cc., with a maximum to 

 minimum range from 62,790 to 120. Twenty-five examina- 

 tions at 176 F. showed an average of only 117, with a 

 range from 300 to 20. The results at 185 F. showed 

 practically the same results as noted at 176 F. Consider- 

 able trouble was experienced with the " scalding on " of 

 the milk to the walls of the machine when milk of high 

 acidity was used. 



The writer 1 tested Reid's pasteurizer at 155 to 165 F. 

 with the following results: in some cases as many as 40 

 per cent of the bacteria survived, which number in some 

 cases exceeded 2,000,000 bacteria per cc. 



Development of pasteurization and pure-culture ripening. 



Since the introduction of this system into Denmark in 

 1890, creamery methods have been completely revolution- 

 ized. At the present time practically all of the butter ex- 

 ported to England is prepared in this way and by far the 

 larger part of that which is consumed at home. There are 

 several different selected commercial cultures that are used. 

 In Sweden, in 1897, 67 per cent of creameries pasteurized 

 their product. 



In Germany the system has been adopted most exten- 

 sively in the north, and may be said to be practically an ex- 

 tension of the Danish system. In southern Germany the 

 method is not employed to any extent. 



In this country considerable agitation has been given 

 the matter, but the process has been but slowly adopted. 

 Under the auspices of the Department of Agriculture at 

 Washington, considerable effort has been put forth in the 



'Russell, Bull. 69, Wis. Expt. Stat. 



