Structural characterisation of EPS of Streptococcus thermophilus S-3 and its application in milk fermentation

The application of Streptococcus thermophilus S-3 into yogurt production was studied and the structural properties of the generated exopolysaccharides (EPS-S3) were characterized. The proposed structure of EPS-S3 was obtained. EPS-S3 contained a high ratio of N-Acetyl-galactosamine with the Mw of 574 kDa, which was higher than that of AR333 (314 kD) leading to higher apparent viscosity. Streptococcus thermophilus strain S-3 was co cultured with Lactobacillus delbrueckii for yogut production which highly increased the acidifying rate and post-acidification rate. The quality of the co-cultured yogurts in terms of apparent viscosity, syneresis capacity, water holding capacity and rheological properties were much better than that by using Lactobacillus bulgaricus only. The production mechanism of EPS-S3 from gene regulated level was also discussed which is helpful to facilitate the application of Streptococcus thermophilus strain into milk production. (c) 2021 Published by Elsevier B.V.

Automated summary

The application of Streptococcus thermophilus S-3 in yogurt production led to the generation of EPS-S3 with high apparent viscosity and quality, when co-cultured with Lactobacillus delbrueckii, it significantly increased the acidifying rate and improved the rheological properties compared to using Lactobacillus bulgaricus only. The production mechanism of EPS-S3 was discussed for potential applications in milk production.