Effects of Tremella fuciformis Powder with Varying Particle Sizes on the Gel Properties of Soy Yogurt

This study aimed to elucidate the mechanisms by which <i>Tremella fuciformis</i> powder (TFP) improves the gel properties of soy yogurt by investigating the effects of TFP particle size on physicochemical properties and rheological behavior, combined with microstructural characterization and intermolecular interaction analyses. The results demonstrated that reducing TFP particle size (from 432.33 µm to 50.10 µm) significantly enhanced its hydration properties and increased the water holding capacity of soy yogurt to 99.44% (<i>p</i> < 0.05). Rheological analysis showed that reduced TFP particle size increased the apparent viscosity, storage modulus, and loss modulus of soy yogurt, consistent with the formation of a denser gel network observed via particle size analysis and SEM. While larger particles disrupted ordered protein cross-linking, smaller TFP particles enhanced soy yogurt gel properties by filling voids, during which volumetric expansion through water absorption reinforced gel matrix continuity. Zeta potential and intermolecular interaction analyses suggested that reduced TFP particle size enhanced non-covalent interactions in soy yogurt. These results indicate that TFP improves the gel properties of soy yogurt primarily through filler effects and protein interactions, providing a valuable reference for formulating stable plant-based yogurt products.