THERMAL DEATH POINTS OF PATHOGENIC BACTERIA IN MILK

Abstract

The earlier work is reviewed with special reference to the thermal death points of members of the typhoid group, tubercle bacilli and pathogenic and non-pathogenic streptococci in milk. Results of tests of pasteurizing equipment at Endicott, New York, are summarized. The efficiency of the continuous flow, pocket type and vat type machines is compared. The 1st tests were conducted with machines with gross defects consisting of leaky valves and insufficient holding time at the desired temperatures for certain portions of the milk. The efficiency of the machines with the recommended safeguards and improvements was tested later and found satisfactory. The new vat type with leak proof valves meets requirements. Models of pasteurizing equipment should be first inspected by qualified experts. Commercial pasteurization is defined as the process of heating milk to approximately 145[degree]F., never lower than 142[degree], holding every portion of it at that temperature for at least 30 minutes, and then promptly cooling to 50[degree].