REPORT OF THE BACTERIOLOGIST. 



THE EFFICIEJ^OY OF A CONTIJ^UOUS PAS- 

 TEURIZER AT DIFFERE^nTT TEMPERA- 

 TURES.* 



H. A. Harding and L. A. Rogers. 



SUMMARY. 



These tests were made by passing mixed whole milk through a 

 Danish continuous pasteurizer. At 70°C. (158'^r.) the efficiency 

 of the continuous pasteurizer varies greatly from day to day. 

 Tests upon 14 different days gave an average of 15,288 living 

 germs per cubic centimeter left in the pasteurized milk, with a 

 maximum of 62,T90 and a minimum of 120 germs. 



At 80° C. (176° F.) the reduction in germ content is both very 

 uniform and very great. Tests upon 25 different days gave an 

 average of only 117 living germs per cubic centimeter in the 

 pasteurized milk, with a maximum of 297 and a minimum of 20 

 germs. 



At 85° C. (185° F.) the average reduction is not more marked 

 than at 80° C. but the range of variation is less. This temperature 

 has the added advantage, according to Dr. Bang, of removing the 

 danger from germs of tuberculosis in the milk. 



Even when the whole milk was heated to 85 °C. the butter did 

 not have a permanent cooked flavor. 



INTRODUCTION. 



An inquiry into the laws which underlie any of the complex 

 commercial processes will progress slowly if each step is deter- 



Reprint of Bulletin No. 172. 



