Natural polysaccharides mediated "low-molecular-bridging" network in fermented soybean protein gels: Interaction,...

This study investigated the interactions, microstructure, and rheological properties of Lactobacillus plantarum JYLP-326-fermented protein gels formed by soybean protein isolate (SPI) and three natural polysaccharides: fucoidan (FU), tremella fuciformis polysaccharide (TFP), and lycium barbarum polysaccharide (LBP). Spectroscopic analysis showed that the peptide fractions of fermented SPI-TFP (FSPI-TFP) in the >100 kDa and 50-100 kDa ranges significantly decreased, while those in the 10-50 kDa and < 10 kDa ranges significantly increased. Microscopic quantification further revealed that the incorporation of natural polysaccharides increased the fractal dimension and decreased the lacunarity. FSPI-TFP exhibited a compact and dense "low-molecular-bridging" network. The rheological results showed that FSPI-TFP exhibited a larger thixotropic area (6491.5 Pa/s), yield stress (145.86 τ₀/Pa), and strain (392.33 %), indicating a more stable shear-resistant structure. Lissajous τ-γ and τ-γ̇ curves showed that as strain amplitude increased, FSPI-TFP exhibited relatively delayed energy dissipation, with stable viscoelasticity. This study will offer novel perspectives for the creation of fermented soy protein products and the expansion of natural polysaccharide applications.