Effect of Deep Eutectic Solvent-Modified Rice Bran Dietary Fiber on Physicochemical Properties of Indica Rice Starch

In this study, rice bran dietary fiber (RBDF) was modified by a deep eutectic solvent (DES) consisting of choline chloride and lactic acid, and the effects of RBDF and its modified version (D-RBDF) on the microscopic morphology, pasting, rheology, and texture properties of indica rice starch were analyzed. The results showed that DES modification enriched cellulose in RBDF, reduced the hemicellulose and lignin contents, and improved the thermal stability and crystallinity of RBDF. Furthermore, D-RBDF significantly increased the pasting temperature and breakdown value of indica rice starch, while significantly reducing the peak viscosity and retrogradation value. It also decreased the storage modulus (G') and loss modulus (G"), and increased the loss tangent (tan δ). The addition of RBDF significantly increased the hardness, stickiness and chewiness of indica rice starch gel, while significantly decreasing the elasticity (P < 0.05). The surface of the starch gel added with D-RBDF was more porous with irregular depressions. Therefore, DES modification affected the composition, structure and properties of RBDF, which in turn changed the interaction between RBDF and indica rice starch. This study provides a theoretical basis for the application of RBDF in whole-grain rice-based products.