The study aimed to develop and characterize composite hydrogels composed of polymerized whey protein (PWP, 10% wt/vol) and Grifola frondosa polysaccharide (GFP, 0%-4% wt/vol) as a natural functional additive for yogurt. The hydrogel structure change was elucidated at the molecular level using simultaneous rheology and Fourier-transform infrared spectroscopy. Results indicated that GFP significantly enhanced the hydrogel's network density and thermal stability through hydrogen bonding and electrostatic interactions, as evidenced by increased particle size, zeta potential, and endothermic peak temperature. Yogurt formulated with 2% PWP-GFP exhibited superior texture (e.g., elasticity and cohesiveness) and water-holding capacity (up to 70.12% ± 1.19% with 3% GFP). Electronic tongue and nose analyses further revealed enhanced umami and overall flavor profile. This study provides a theoretical and practical foundation for the application of natural protein-polysaccharide complexes in high-quality dairy products.

The development of natural biopolymers to improve the structural and textural defects of whey protein in acidic dairy products is of great interest. This study investigated the interaction between Phellinus linteus polysaccharides (PLPs) and heat-induced polymerized whey protein (PWP), and its application in goat milk yogurt. The physicochemical properties and interaction mechanisms of PWP-PLP composite hydrogels (with 1–4% PLP) were characterized using particle size, DSC, and synchronous rheology and Fourier transform infrared spectroscopy. The results show that PLP increased hydrogel particle size, absolute zeta potential (from −34.98 mV to −42.26 mV), and denaturation temperature (from 102.33 °C to 112.57 °C), indicating the enhanced stability. SR-IR analysis revealed intensified hydrogen bonding and protein secondary structure rearrangement. Incorporated into yogurt, the optimal composite (10% PWP with 3% PLP) significantly improved water-holding capacity (by 20–30%), storage modulus (G′), and produced a denser microstructure with superior texture. This work demonstrates that PLP is an effective natural modifier for constructing stable protein–polysaccharide hydrogels to enhance yogurt quality.