Bitterness in Milk Cultures of Streptococcus Cremoris

Abstract

Four strains of S. cremoris were studied for their ability to produce a bitter flavor in milk cultures. Two strains produced definite bitterness when incubated at 32[degree]C. Although the defect developed at 22 C, it was produced more consistently and with a more intense flavor at 32[degree]C. The earliest the flavor could be detected, with one of the bitter strains, was after 48 hr. incubation at 32 C. There may be a relationship between onset of bitterness, decrease in viable count and proteolysis (measured by increase in trichloroacetic-acid soluble (TCA) N). Viable counts for all strains decreased between 30 and 48 hr. incubation at 32 C. Both bitter strains exhibited greater proteolysis during exponential growth in milk and continued to produce gradual increases in TCA soluble N up to at least 20 days incubation. Non-bitter strains exhibited increases in proteolytic activity up to 7 days incubation; beyond this period little or no increases were apparent.