550 



STATE BOARD OF AGRICULTURE. 



Anotlicr method used for comparison is the same as the above de- 

 scribed with the exception that a laj^er of sterile liquid paraffin about 

 one-half inch in depth was placed upon the medium just before the ex- 

 posure in the water bath. The paraffin, which serves to exclude the air 

 and to prevent the possible formation of a surface pellicle, remained in 

 the tubes during the incubation period. 



Sternberg Bulbs also were used for comparison. They Avere filled 

 with the suspension, exposed in a Avater bath at the desired temperature 

 for the required length of time, cooled and emptied into tubes of litmus 

 milk. 



VARIATION IN THE TEMPERATURE OF CREAM DURING PASTEURIZATION. 



A "Perfection" pasteurizer (200 gallon capacity) installed in the Col- 

 lege Dairy Department was used for this work. It contains a block tin 

 spiral tube through which water of any desired temperature can be 

 pumped. The spiral is made to rotate and to serve as a stirring device. 

 Observations were made in cream which was pasteurized by the holding 

 process at 145° F. for 20 minutes and which was used for churning in 

 the College dairy. The temperature was read at intervals at a depth of 

 about four inches near the corners and in the center of the pasteurizer 

 and also in the surface of the cream. The data obtained (Table I) show 

 a very slight variation in the temperature of the cream at different 

 points during the pasteurization and indicate that the process employed 

 Avould be considered efficient. 



TABLE 1.— VARIATION IN THE TEMPERATURE OF CREAM DURING PASTEURIZA- 

 TION BY THE HOLDING PROCESS. 



*Taken with a dairy thermometer. 



tTalven with a certified thermometer graduated -n 0.1' 



'C. 



