Physicochemical, microbiological and sensory characterization of yogurt fermented by Weissella confusa SW1 and traditional starters

Starter cultures play important roles in the quality and functional activity of yogurt. In this study, a novel strain Weissella confusa SW1 was isolated from naturally fermented milk. The potential application of this strain in yogurt preparation was investigated and the unique qualities it conferred on yogurt was characterized. W. confusa SW1 could efficiently metabolize lactose and galactose, and the whole-genome sequencing showed that it has a complete Leloir metabolic pathway. Besides, W. confusa SW1 had strong antioxidant capacity, and could significantly promote the growth of Streptococcus thermophilus. Subsequently, W. confusa SW1 was co-cultured with traditional starters (Lb. bulgaricus and S. thermophilus) to prepare yogurt. The results showed that the scavenging rates of DPPH and ABTS radicals of W. confusa SW1 fermented yogurt increased from 79.51% to 85.19% and 80.14% to 85.47%, respectively. Meanwhile, the viable bacterial counts of Lb. bulgaricus and S. thermophilus were increased in yogurt when co-cultured with W. confusa SW1. Furthermore, the addition of W. confusa SW1 reduced the curd time and improved the water holding capacity of yogurt. Thus, this study laid a theoretical foundation for the development of functional yogurt with the application of W. confusa SW1.