Effect of Incubation Temperature and Heat Treatments of Milk from Cow and Buffalo on Acid and Flavor Production by Streptococcus thermophilus and Lactobacillus bulgaricus

Abstract

Variations in production of acid and acetaldehyde and proteolytic activity by pure and mixed cultures of Streptococcus thermophilus and Lactobacillus bulgaricus in response to incubation temperature were determined using cow and buffalo milk. S. thermophilus and the mixed culture produced more acid and acetaldehyde at 37 than at 42 C, while the reverse was true for L. bulgaricus in both types of milk. The largest amount of acid was produced by S. thermophilus in both types of milks heated at 65 C for 30 min, while L. bulgaricus produced the maximum amount of acid in milks heated at 85 C for 10 min. In the mixed culture, increased acid and acetaldehyde production were noted in milk sample steamed for 30 min.