Effect of transglutaminase on the interaction of protein and rice starch

The present study aims to investigate the effects of endogenous protein (rice protein, RP) and exogenous proteins (corn protein, CP, and wheat protein, WP) on the physicochemical properties of rice starch under the action of transglutaminase (TG). The findings indicate that, the interactions between exogenous proteins with rice starch are relatively weak. However, with the catalysis of TG, both endogenous and exogenous proteins tightly encapsulate rice starch granules, forming a dense microporous network structure. This phenomenon led to a reduction in starch expansion coefficient and amylose leaching, resulting in an increase in the onset temperature and a notable decrease in viscosity and digestibility. Among them, endogenous protein exerted the greatest influence on the gelatinization properties of rice starch, whereas exogenous protein had the most significant impact on its digestibility. Specifically, the order of influence on the gelatinization characteristics is RP > CP > WP, and for digestibility, it is WP > CP > RP. Furthermore, under the action of TG, both endogenous and exogenous proteins significantly enhanced the short-range ordered structure of starch molecules, contributing to higher crystallinity and a more ordered A-type structure. In conclusion, this study provides a theoretical basis for the construction of starch functional foods.