MARKET MILK 



169 



Effect of Stirring Milk on Rapidity of Cooling 







Stirred at Intervals 

 of 10 Minutes 



Not Stirred 



Difference in 

 Temperature 



(Degrees 

 Fahrenheit) 



DUE TO 



Can 



Temperature of milk 

 (degrees Fahrenheit) at 



Temperature of milk 

 (degrees Fahrenheit) at 





Beginning of 

 experiment 



End of 20 

 minutes 



Beginning of 

 experiment 



End of 20 

 minutes 



Stirring 



1 '-. . . 



95° 



68° 



95° 



75° 



7° 



2 . 





95° 



73° 



95° 



85° 



12° 



3 . 





90° 



75° 



92° 



80° 



5° 



4 . 





96° 



73° 



96° 



79° 



6° 



5 . 





98° 



71° 



98° 



88° 



17° 



6 . 





95° 



69° 



95° 



78° 



9° 



7 . 





98° 



73° 



98° 



76° 



3° 



8 . 





98° 



73° 



98° 



88° 



15° 



9 . 





96° 



72° 



98° 



86° 



14° 



10 . 





99° 



73° 



99° 



82° 



9° 



an effective check on the development of bacteria, and a cor- 

 responding improvement in the quality of the milk. The 

 same authors give the effect of frequency of stirring as follows : 



Frequency of Stirring on Rapidity of Cooling, when Cans are 

 Set in Ice Water, at End of One Hour 



(Adapted from Ross and Mclnerney) 



Trial No. 



Not Stirred 

 at All 



Stirred 



every 



Stirred 

 every 



Stirred 

 Continu- 





5 Min. 



10 Min. 



ously 



1 ....... . 



61° 



■ 45° 



46° 



39° 



2 ....... . 



72° 



54° 



55° 



54° 



3 



67° 



53° 



53° 



47° 



4 



63° 



57° 



58° 



53° 



5 



57° 



48° 



49° 



41° 



6 



56° 



52° 



52° 



43° 



7 ....... . 



58° 



53° 



58° 



44° 



8 



59° 



55° 



55° 



46° 



9 



58° 



55° 



55° 



46° 



10 



61° 



54° 



54° 



40° 



Average ...... 



61.2° 



52.6° 



53.5° 



45.3° 



