Green Flavor Defect in Lactic Starter Cultures

The diacetyl-to-aeetaldehyde ratio was found to be approximately 4:1 in desirably flavored mLxed-strain butter cultures. When the ratio of the two compounds was lower than 3:1, a green flavor was observed. Acetaldehyde utilization at 21 C by Leuconostoc citrovorum 91404 was very rapid in both acidified (pH 4.5) and nonacidifled (pH 6.5) milk cultures. The addition of 5 ppm of acetaldehyde to nonacidifled milk media prior to inoculation greatly enhanced growth of L. citrovorum 91404 during incubation at 21 C. A proposed mechanism of acetaldehyde utilization and its effect on associative growth in mixed-strain butter cultures is discussed. Combinations of single-strain organisms demonstrated that the green flavor defect can result from excess numbers of Streptococcus lactis or Streptococcus diacetilactis in relation to the L. citrovorum population.