Evaluation of Pediococcus pentosaceus strains as probiotic adjunct cultures for soybean milk post-fermentation

Soybean milk is an economical substitute for dairy products. Pediococcus pentosaceus has been used as a food additive to improve taste, nutrition, and food safety. In this study, four P. pentosaceus strains (CICC 24444, QK-1, MQ-1 and RQ-1) isolated from various food sources and known to exhibit broad-spectrum antibacterial activities were used to ferment soybean milk, and their fermentation characteristics and the properties of the resulting beverages were evaluated. The results revealed that the P. pentosaceus strains can inhibited the growth of five types of pathogenic bacteria (Salmonella enterica subsp. enterica serotype Enteritidis, Yersinia enterocolitica, Shigella dysenteriae, Escherichia coli, and Staphylococcus aureus), and their in vitro survival rates in the simulated stomach and intestinal environments were above 90%, satisfying the probiotic requirements. Isomaltose oligosaccharide was used as a protective agent to resist low-temperature freeze-drying damage and ensure a high survival rate, and P. pentosaceus was directly injected into fermented soymilk. The acidification of fermented soybean milk was the weakest with P. pentosaceus QK-1, and the viable bacterial counts of all strains were stable after 28 days of storage. After fermentation, the antioxidant ability was enhanced. Arginine and beta-alanine levels increased after fermentation, and the adjunct culture of P. pentosaceus QK-1 increased proline levels. Our data indicate that P. pentosaceus QK-1 is a suitable strain for the development of functional plant-based beverages.

Automated summary

This study evaluated the fermentation characteristics and properties of soybean milk fermented by four Pediococcus pentosaceus strains. The results showed that these strains exhibited antibacterial activity, with survival rates above 90% in simulated gastrointestinal environments, satisfying probiotic requirements. Among the strains, QK-1 showed the weakest acidification of fermented soybean milk, and all strains maintained stable bacterial counts after 28 days of storage, with enhanced antioxidant ability post-fermentation.