Effect of a co-fermentation system with high-GABA-yielding strains on soymilk properties: microbiological, physicochemical, and aromatic characterisations

Biosynthesis is the safest method for preparing GABA; however, there are not enough GABA-producing strains to provide an effective resource. The purpose of this study was to determine the feasibility of using Lactobacillus fermentum SMN10-3(A) and Lactococcus lactis SMN15-6(B) to study the effects of strain complex pairing on the GABA formation, flavour, and metabolic pathways of fermented soymilk. It was found that group A2B1 had the highest acid production rate, GABA yield (1.76 +/- 0.01 mg/mL), and flavour compound content. A total of 55 differential metabolites were produced after fermentation, of which 28 dominated by hexanal were significantly downregulated and 26 dominated by alcohols were significantly upregulated. The significant metabolic pathways involved were D-alanine, taurine and hypotaurine, and selenocompound metabolism. Finally, the components contributing to the aroma of fermented soymilk were identified, which included 2-pentylfuran and 2-butyl2-octenal. These results provide a theoretical basis for future research on GABA-rich fermented foods.

Automated summary

The aim of this study was to investigate the effects of two bacterial strains on the formation of γ-aminobutyric acid (GABA), flavor, and metabolic pathways in fermented soymilk. The results showed that the A2B1 combination exhibited the highest acid production rate, GABA yield, and flavor content. After fermentation, 55 differential metabolites were produced, with 28 hexanal-dominated metabolites significantly downregulated and 26 alcohol-dominated metabolites significantly upregulated. Significant metabolic pathways included D-alanine, taurine and hypotaurine, and selenocompound metabolism. Furthermore, 2-pentylfuran and 2-butyl2-octenal were identified as contributing to the aroma of fermented soymilk. These findings provide a theoretical basis for future research on GABA-rich fermented foods.