Oxidative Metabolism of Lactic Acid Bacteria Associated with Pink Discoloration in Italian Cheese

Abstract

Metabolism of Lactobacillus bulgaricus ATCC 12278 and Lactobacillusbelveticus ATCC 10797, associated with pink discoloration of cheese, was compared to that of Lactobacillus lactis ATCC 11061 which never caused the defect. Hydrogen peroxide was produced in various media by L. lactis but did not accumulate during growth of the other two strains. Cell suspensions of L. lactis consumed oxygen rapidly in the presence of glucose and lactate; the other strains were moderately active. Added tyrosine increased the ultimate intensity of pink discoloration in Romano cheese made with Lactobacillus bulgaricus and Lactobacillus belveticus; ascorbate, pyruvate, and fumarate accelerated rate of development of the defect. These additives did not induce the defect in cheese made with Lactobacillus lactis or Streptococcus tbermopbilus strain Mc which never were associated with the defect. Sodium thioglycolate and glutathione prevented the discoloration. © 1977, American Dairy Science Association. All rights reserved.