In Vitro Digestion, Physicochemical and Structural Properties of Rice Starch Dual-Treated with Radio Frequency Dry Heating and Annealing Treatment

Abstract Radio frequency dry heating treatment combined with annealing treatment (RFDHT-ANN) was applied in this study to investigate the effects of the combined treatment on the digestibility, pasting properties, and multiscale structure of rice starch (RS). In practice, the combined modification treatment did not change the crystal type but resulted in a change in the microscopic morphology of RS. The dual treatment improved the amylose content, solubility, particle size, relative crystallinity and gelatinization transition temperature but declined the starch's swelling power. The lowest enzymatic digestibility was found with a decrease of 9.05% of rapidly digestible starch but an increment of 1.69% of slowly digestible starch and 7.38% of resistant starch. Compared with native starch, the characteristic peak of modified starches at 20.2° (2θ) was weakened. Furthermore, the dual treatment noticeably decreased the gelatinating viscosity of RS. This study provides innovative ideas for improving starch-based, slowly digestible foods in the future.