Enhanced shelf-life of tofu by using bacteriocinogenic Weissella hellenica D1501 as bioprotective cultures

Bacteriocinogenic Weissella hellenica D1501 was originally isolated from Chinese Dong fermented meat, showing a relatively good growth and sufficient acid development in soymilk. Investigation of the antagonistic activities of W. hellenica D1501 was conducted by co-culturing with spoilage and pathogenic bacteria (i.e. Kurthia gibsonii, Staphylococcus aureus and Escherichia coli) in soymilk. The proliferations of the three undesired strains were suppressed and the bacterial populations decreased to undetectable level after 36 h of co-cultures. An innovative tofu (designated as LAB tofu) was a novel type of tofu coagulated by both acid and enzyme together through the using of W. hellenica D1501 combined with MTGase (microbial transglutaminase). Compared with tofu prepared with traditional coagulants, W. hellenica D1501 in LAB tofu could significantly suppress the microbial spoilage and extend the shelf-life based on microbiological analyses. During the storage periods at different temperatures, LAB tofu was observed bacteriocin activities and significantly increased amounts of various antimicrobial volatile compounds, which might be in partly responsible for spoilage retardation and shelf-life extension. In conclusion, W. hellenica D1501 can be used as bioprotective cultures for extending shelf-life and improving the safety of tofu.