Bacteriology of Milk Held at Farm Bulk Cooling Tank Temperatures

Raw milk samples from different farms were held at 36° F., 38° F., 45° F., and at 38° F. with periodic warming to 45° F. or 50° F., and standard, thermoduric and psychrophilic plate counts were made daily for four days. Little increase in bacterial numbers took place in three days at 36° F. At higher temperatures significant increases occurred in port of the samples within one or two days. A 45° F. storage temperature was too high. No correlation was found between farm source of milk and growth of bacteria. Psychrophiles grew better in summer than in winter milk.