Physicochemical Properties and Functional Characterization of Buckwheat Type 3 Resistant Starch Prepared by Various Treatment Methods

Resistant starch (RS) has garnered significant attention for its health benefits and controllable processing safety. In this study, buckwheat type 3 resistant starch (RS3) was prepared using autoclaving (A-BRS), microwaving (M-BRS), and autoclaving combined with enzyme treatment (AE-BRS). The physicochemical structures and functional properties of the modified starches were compared. Results showed that, compared to native buckwheat starch, the particle size volume mean diameter (VMD) of BRS increased significantly from 9.67 μm to 54.21–59.81 μm, with a crystalline structure transformation from A-type to B+V-type and an increase in gelatinization enthalpy ( ΔH ) to 3.26–7.26 J/g. Among the three resistant starches, A-BRS exhibited the largest granule size, highest water-holding capacity, and greatest transparency, while M-BRS had the roughest surface. Notably, AE-BRS, with an amylose content increased to 34.71%, exhibited enhanced relative crystallinity and short-range ordered structure, leading to higher solubility and thermal stability, with an RS content reaching 21.01%. The composite preparation of resistant starch is anticipated to become a significant trend in the future. These findings offer valuable insights for the industrial development and production of buckwheat RS3.