Abstract: In order to achieve slow digestion of starch and maintain the stability of postprandial blood glucose, starch-apigenin complex (SAC) was prepared by ball-milling method, and the in vitro digestibility of SAC was evaluated. Using one-factor-at-at-time method, the optimal conditions for the preparation of the complex were determined to be starch:apigenin mass ratio of 5:1 and milling time of 30 h, giving a content and percent complexation of apigenin of 71.5 mg/g and 35.7%, respectively. Characterization by scanning electron microscopy (SEM), X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis showed that the morphology of the starch granules was altered by ball-milling with some of them being ruptured, and apigenin was adhered to the starch granules and gathered together. The crystalline diffraction peaks of apigenin in SAC disappeared after ball-milling treatment, and its characteristic absorption peaks disappeared at 1 081 and 700–800 cm-1. The thermal stability of corn starch could be improved by complexation with apigenin. In vitro digestion experiments showed that SAC with mass ratio of corn starch to apigenin of 5:1 had the lowest digestion rate of 18.8% after being incubated for 5 h, indicating that the presence of apigenin increased the anti-digestibility of starch, and the higher the content of apigenin in the complex, the lower the digestion rate of starch.

Key words: corn starch, apigenin, ball-milling, complex, digestibility