122 



Dairy Bacteriology. 



THERMAL 

 DEATH POINT 



MAXIMUM 

 GROWTH POINT 

 BLOOJ) HEAT- 



MINIMUM 



'GROWTH POINT 



FIG. 25. Diagram showing tem- 

 perature changes in pasteurizing, 

 and the relation of same to bac- 

 terial growth. 



Shaded zone represents limits 

 of bacterial growth, 50-109 F. 

 (10-43 C.), the intensity of shad- 

 ing indicating rapidity of develop- 

 ment. The solid black line shows 

 temperature of milk during the 

 process. The necessity for rapid 

 cooling is evider.t as the milk fal's 

 in temperature to that of growing 

 zone. 



