Influence of Different Sterilization Conditions on the Growth and Exopolysaccharide of Streptococcus thermophilus and Co-Cultivation with Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1

Abstract

The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product’s qualities. In this study, the fermentation properties of Streptococcus thermophilus, alone and in combination with Lactobacillus delbrueckii subsp. bulgaricus, were evaluated in skim milk that had been subjected to distinct sterilization conditions. Growth, organic acid generation, and EPS production were determined using pasteurized or autoclaved milk. When S. thermophilus was cultivated in pasteurized skim milk, the growth was strain-dependent. On the other hand, growth of S. thermophilus was accelerated in autoclaved milk. Exocellular polysaccharide (EPS) production by L. bulgaricus was not affected by the combination of S. thermophilus strains. Thus, we observed that yogurt fermented by L. bulgaricus was minimally affected by the combination of S. thermophilus strains; growth of L. bulgaricus was maintained under the constant environment. These results should facilitate the development of fermented milk produced from L. bulgaricus in the dairy industry.