Improving soy sauce quality via co-fermentation with indigenous Tetragenococcus: Reducing biogenic amines and enhancing flavor

Soy sauce, a traditional fermented soybean condiment originating in Asia, is now enjoyed worldwide. As its popularity grows, ensuring both its safety and high quality has become increasingly important. In industrial production, starter cultures are essential for controlling microbial communities and enhancing the safety and quality of the product. This study initially screened bacterial starter cultures with the ability to degrade biogenic amines (BAs), followed by their mono- or co-inoculation in soy sauce fermentation. The results showed that mono-inoculation with Tetragenococcus halophilus C88, Tetragenococcus halophilus C13, Lactiplantibacillus plantarum H6 and Staphylococcus piscifermentans S1 reduced BAs levels by 28.13 %, 29.55 %, 18.90 % and 14.63 % respectively. Concurrently, these treatments increased the total volatile organic compounds (VOCs) by 28.00 %, 82.68 %, 46.67 % and 80.13 % respectively. Notably, co-inoculation of T. halophilus C88 with Lpb. plantarum H6 led to superior BA degradation decreased by 31.39 %, while co-inoculating T. halophilus C13 and S. piscifermentans S1 resulted in a greater increase in VOCs compared to mono-inoculation, achieving a 105.07 % rise compared to natural fermentation. These findings indicate that synergistic interactions between co-fermentation starters can improve soy sauce quality. Additionally, the research highlights the potential of using complementary starter cultures to influence the metabolic pathways of key VOCs, offering valuable insights for enhancing both the safety and flavor profiles of soy sauce in industrial production.