Abstract: The purpose of this investigation was to explore the fabrication of a self-assembled complex of potato starch (PS) and pomegranate peel polyphenols (PP) by ball milling and to investigate its digestion characteristics. The impact of ball milling time, ball milling speed, and PS/PP mass ratio on the total polyphenol content and digestion characteristics of the self-assembled complex was investigated. Then, the formed product was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The results showed that the content of total polyphenols was (19.91 ± 0.32) mg/g in the product obtained under the following conditions: milling time 10 h, rotational speed 500 r/min, and mass ratio of PS to PP 1:0.15. The SEM results showed that many cracks and gullies appeared on the surface of the product, which was accompanied by an agglomeration phenomenon. The XRD results showed that the crystalline domain of starch was destroyed by ball milling, and the intensity of the diffraction peak became weakened or even disappeared, indicating that the granules were changed into an amorphous structure. The FTIR results showed that the absorption peak at 3 600–3 400 cm-1 was enhanced, which illustrated that PP and PS were self-assembled through hydrogen bonds. Hence, ball milling can be used to fabricate PS/PP self-assembled complex. The TGA results demonstrated that the thermal stability of the self-assembled complex was improved. Furthermore, in vitro simulated digestion and in vitro simulated gastrointestinal release tests showed that the proportion of resistant starch in the complex was significantly increased, which was beneficial to maintain the stability of the guest molecules during the digestion process, and allowed the targeted release of polyphenols in the large intestine and colon, enabling the guest molecules to exert their functions better, thereby improving their bioavailability.

Key words: potato starch; pomegranate peel polyphenols; ball milling treatment; self-assembly; resistant starch