Effect of Microwave-Assisted Heat–Moisture Treatment on Structure, Physicochemical Properties and In Vitro Digestibility of Wheat Starch

Wheat starch serves as a major dietary carbohydrate. Optimizing its structural and functional properties is essential for developing health foods. In the present study, microwave-assisted heat–moisture treatment (MHT) was applied to modify wheat starch and the effects of the physical treatments on its structure and digestibility were investigated. X-ray diffraction analysis revealed that the crystallinity of wheat starch slightly decreased after MHT. Ion chromatography revealed changes in the chain length distribution of wheat starch after modification, with a continuous increase in short-chain components over treatment time. MHT enhanced the enzymatic resistance of wheat starch, which resulted in a resistant starch content of 36.89% after 1.5 h of MHT. Excess heat disrupted the ordered structure of starch when the treatment was extended to 2 h, leading to a slight reduction in enzymatic resistance. The study provided a theoretical basis for designing functional starch ingredients through low water content physical treatment.