Tailoring texture for dysphagia diets: Unraveling the synergistic role of protein and blended vegetable oil in softening starch gels.

Starch-based gels are an ideal food choice for individuals with dysphagia. This study investigated how interactions between starch, soy protein isolate, and blended vegetable oil regulate the gel network formation, focusing on texture, rheology, water distribution, microstructure, and thermal decomposition behavior. Vegetable oil raised the gelatinization temperature of rice starch by 7.4 °C and reduced the apparent viscosity of the gel by nearly half, with η50 at 7.73 Pa·s. Vegetable oil was distributed as discrete oil droplets, while protein was embedded in the starch matrix as aggregates or smaller clusters. The formation of amylose-lipid complexes consumed amylose and inhibited the formation of double-helix structures, leading to reductions in gelatinization enthalpy, relative crystallinity, and hydrogen bond strength. Proteins adsorbed preferentially at the oil-water interface to form an interfacial film, preventing oil droplet aggregation. The absolute zeta potential value improved to 30 mV, while the complexation index lowered by 16%. Furthermore, the introduction of proteins decreased the number of ordered aggregates within the gel system, thereby forming a loose network structure. Overall, this study provides novel insights into elucidating the key interaction mechanisms in multicomponent systems.