FATE OF COLIFORM BACTERIA IN BUTTERMILK1

Coliform bacteria in buttermilk decreased on storage at 4 C and 87 C. Counts decreased at 20 C when the initial inoculum was low but increased when it was high. The change in the number of coliform bacteria was not correlated with either the total acid or acetic acid concentrations, or with their kinetics. In 10% skim-milk lactic and acetic acid had complementary inhibitory effects on coliform bacteria, except when the acetic acid concentration was below 10%, then the interaction between the two acids was not consistent.