Effect of whey protein fibrous aggregates on swallowing properties and retrogradation behavior of whey protein–wheat starch composite soft gel

BACKGROUND While our previous investigation established that whey protein fibrillar aggregates (WPF) synthesized at 85 °C for 5 h demonstrate superior starch retrogradation inhibition capabilities, their functional synergy with whey protein–wheat starch (WP‐WS) composite gel systems remains underexplored. This study aimed to assess the dose‐dependent effects of WPF on swallowing‐related rheology and starch retrogradation mechanisms in WP‐WS gels. RESULTS A model dysphagia food system was engineered under the International Dysphagia Diet Standardization Initiative (IDDSI) framework, employing a sequential optimization approach: initial screening of WP/WS mass ratios (10% total solids) followed by WPF supplementation (0–20% w/w). Rheological analysis revealed that gels with 10% total solids and a WP/WS ratio of 9:1 exhibited optimal viscosity, storage modulus ( G ′) and loss modulus ( G ″), meeting IDDSI Level 6. Subsequent WPF incorporation induced 151% viscoelastic enhancement with G ′ final = 786.4 Pa, 46.12% yield stress reduction (57.75 versus 107.19 Pa in controls) and 19.4‐fold decrease in creep recovery rate ( γ e / γ v = 0.20 versus 3.84). Additionally, WPF elevated water‐holding capacity by 12.82%, enhanced gel hardness and elasticity and reduced starch retrogradation by 28.97% over14 days of storage ( P < 0.05). Structural analyses indicated that WPF modified hydrogen bonding interactions and protein secondary structure, decreasing β ‐turn content while increasing α ‐helix and random coil configurations. Fourier transform infrared deconvolution revealed WPF‐mediated hydrogen bond redistribution, correlating with enhanced water immobilization and delayed amylopectin reassociation. CONCLUSION WPF enhances the swallowing safety/textural stability of WP‐WS gels. It offers a theoretical and technical foundation for designing dysphagia‐friendly foods with delayed retrogradation and regulated rheological properties.