Production of Bitter Flavor Components by Lactic Cultures

A bitter strain and a nonbitter strain of Streptococcus cremoris were grown in skimmilk and in various media with and without casein.The cultures were freezedried, then extracted with chloroformmethanol.Both strains produced bitter flavor components in skimmilk; the bitter strain produced considerably more than the nonbitter strain.Bitter flavor cmnponents were extracted from the whey and curd portions of the culture.However, incubation of curd only as compared to incubation of the entire skimmilk culture, produced more bitterness.Typical bitter flavor was not produced when cultures were grown in defined media containing amino acids as a source of nitrogen or in Elliker's medimn.Cells grown in Elliker's medium containing casein, produced typical bitterness.Thus proteolysis of casein, rather than de novo synthesis by the bacteria, is the source of bitter flavor components.