Enhancing Effect of Flammulina velutipes Polysaccharide on Gelation Properties of Soybean Protein Isolate and Structural Characterization of Mixed Gels

Flammulina velutipes polysaccharide (FVP) was added to soy protein isolate (SPI) hydrogels and subjected to heat treatment to improve the gel strength, water-holding capacity and thermal stability. The stability of FVP-SPI hydrogels was further analyzed in terms of their secondary and tertiary structures and intermolecular forces. The results showed that heat treatment and addition of FVPsignificantly improved the water-holding capacity of SPI hydrogels, and increased the enthalpy change of denaturation (ΔH) by 25.46%, thereby significantly improving hydrogel stability. Hydrophobic interactions, disulfide bonds and electrostatic interactions were the major driving forces for the formation of heat-induced FVP-SPI hydrogels. The addition of FVPimproved the electrostatic interactions and caused transformation of α-helix into β-sheets in the hydrogels, surface exposure of the tryptophan residues in SPI and enhanced hydrophobicity. The enhancement of SPI hydrogels by FVPprovides a reference for the development and application of SPI hydrogels.