Abstract
This study investigated the quality evolution of soybean products (soymilk, tofu, dried bean curd) through mixed-strain fermentation with Lacticaseibacillus rhamnosus CICC 6151 and Saccharomyces cerevisiae AS2.400 under optimized conditions (7% inoculum, pH of 5.2, 85 °C/50 min thermal treatment). Physicochemical, structural, and microbial dynamics were systematically analyzed. Key results demonstrated that probiotic tofu exhibited superior water-holding capacity (82% WHC vs. 65% in traditional variants) and enhanced protein retention (Δ + 2.4% during storage), linked to microbial-mediated structural stabilization. Mixed fermentation induced substrate competition (S. cerevisiae biomass: OD(560) of 1.2 at 10 h vs. L. rhamnosus OD(600) of 1.0 at 25 h; ANOVA p < 0.001), driving pH-dependent protein network formation (isoelectric precipitation at pH of 4.8 ± 0.1) and volatile profile divergence (PCA explained 82.2-89.1% of variance). Probiotic variants maintained chromatic stability (ΔE < 15 vs. traditional ΔE > 23) and textural integrity (23% lower deformation under compression), correlated with secondary structure preservation (β-sheet increased by 10% in FTIR analysis). These findings establish synergistic microbial-metabolic regulation as a strategy for developing functional bean products with enhanced nutritional and sensory properties.