PASTEURIZING MILK. 



23 



THE CREAM LINE AND FLAVOR OF PASTEURIZED MILK COOLED 

 BY VARIOUS METHODS. 



In the consideration of the process of bottling hot pasteurized 

 milk followed by slow cooling it is of practical importance to know 

 what effect such a process will have on the cream line and flavor of 

 the milk. Several experiments were made to determine the effect on 

 these points. Milk was pasteurized, and hot 500-cubic-centimeter 

 graduated cylinders were filled with hot milk up to the 500-cubic- 

 centimeter mark. Together with the cylinder of hot pasteurized 

 milk one cylinder was filled with raw milk and one with pasteurized 

 milk which had been cooled to 50° F. in 15 seconds' time by running 

 through- a coil immersed in brine. The method of cooling the hot 

 cylinders of pasteurized milk was varied considerably, as may be seen 

 from Table 8. After holding the milk for 24 hours at 45° F. the 

 numbers of cubic centimeters of cream were read off directly from 

 the graduations on the cylinder. This method, of course, gave a very 

 accurate means of determining the effect of heating and cooling on 

 the cream line; in fact it was too accurate, since considerable dif- 

 ferences in the cream line by this method of measurement were not 

 apparent in bottled milk. 



Table 8. — Cream-line experiments with raw millc and millc pasteurised at 1^5° F. 



for 30 minutes. 



Experi- 

 ment 

 No. 



• Process. 



Cubic centimeters of 

 cream in 500 c. c. 

 cylinder after 24 



hours' refrigeration 

 at 45° F. 







64 5 



1 



Pasteurized milk: 



Cooled quickly in 15 seconds to 50° F. and held in refrigerator at 45° F. . 



Cooled slowly in air blast for 45 minutes and placed in refrigerator at 



45° F 



64.5 

 65 





Held above 105° F. for 3 hours, cooled in ice water, and placed in re- 



64 5 







65 



2 



Pasteurized milk: 

 < Cooled in 15 seconds to 50° F. and placed in refrigerator at 45° F 



Cooled slowly in air blast for V s hours and placed in refrigerator at 45° F . 



Held above 100° F. for 1?, hours and placed in refrigerator at 45° F 



[Raw milk lost ". 



62.5 

 52.5 

 52.5 



3 



Pasteurized milk: 



Cooled in 15 seconds to 50° F. and placed in refrigerator at 45° F 



Cooled slowly for 30 minutes in air blast, cooled quickly in brine, and 



83 

 85 





Held above 100° F. for 3 hours, cooled quickly in brine, and placed in 



90 









4 



Pasteurized milk: 



Cooled in 15 seconds to 50° F. and placed in refrigerator at 45° F 



Cooled slowly in air blast for 2\ hours, cooled in ice water, and placed in 



75 

 69 





Held above 100° F. for 2 J hours, cooled in ice water, and placed in refrig- 



75 







80 



5 



Pasteurized milk: 



Cooled in 15 seconds to 50° F. and placed in refrigerator at 45° F 



Cooled slowly in air blast for 2 hours and placed in refrigerator at 45° F . . 

 After cooling in air blast for 2 hours the milk was cooled quickly in 



68 

 55 



62 





Held above 100° F. for 5 hours and placed in refrigerator at 45° F 



After holding above 100° F. for 5 hours the milk was cooled quickly 



55 

 62 









