Insight of soy protein isolate to decrease the gel properties corn starch based binary system: Rheological and structural investigation

Dysphagia has become a growing concern for elderly individuals, and starch-based gel foods is expected to become one of the foods easy to swallow. This study investigated the effects of soy protein isolate (SPI) on the sol-gel behavior, rheological, structural and gel properties of corn starch (CS). SPI raised the gelatinization temperature but reduced enthalpy values, inhibiting the gelatinization of CS. There was a reduction of rheological properties in CS-SPI system, involving apparent viscosity, modulus, and shear structural recovery properties, while SPI increased the Tan δ, creep-recovery, and thixotropic properties. Structural analysis demonstrated that SPI introduction altered the lamellar structure, increased the relative crystallinity, and decreased the hydrogen bond strength and order degree in CS-SPI gels, forming a weaker gel network. As a result, the texture profiles such as hardness, gumminess, and chewiness were decreased from 308.60 g to 64.98 g, 285.44 g–50.62 g, and 279.66 g–50.15 g, respectively, whereas the gel strength of CS-SPI gel decreased from 123.91 g to 45.78 g. This study provided foundations for the production of gel food suitable for swallowing.