Preparation, structure characterization, and in vitro bioactivity of yam starch-polyphenol complex

Abstract

Chinese yam (Dioscorea opposita Thunb.), with medicinal and edible properties, holds a significant position in both traditional medicine and food in China. It is rich in resistant starch (RS), which imparts various beneficial effects, including anticonstipation, regulation of blood lipids, and prevention of gastric ulcers. However, the resistance of native yam starch to digestion diminishes during cooking, necessitating suitable modifications. In this article, yam starch was complexed with five different polyphenols to create RS5. The goal was to explore how these diverse polyphenols influence the physicochemical characteristics and bioactivities associated with yam RS. Yam starch-polyphenol complexes, involving five different polyphenols, namely, magnolol (MAG), ferulic acid (FA), resveratrol (RES), apple polyphenols (APs), and green tea polyphenols (GTPs), were prepared. The investigation encompassed the assessment of physicochemical properties, structural traits, in vitro cholate binding capacity, and in vitro antidigestive effects of these complexes. The results highlight the pronounced affinity of MAG for yam starch, followed by FA. Fourier transform infrared spectroscopy reveals that starch-polyphenol binding primarily involves noncovalent interactions. X-ray diffraction analysis discloses V-type crystal structures in YS-MAG, YS-APs, and YS-GTPs complexes. The incorporation of polyphenols reduces the thermal stability of starch while enhancing its in vitro cholate binding capacity, restraining starch digestion, and elevating RS content. Notably, YS-FA exhibits an impressive RS content of up to 54.15%. In addition, YS-MAG and YS-FA significantly enhance the production of short-chain fatty acids. These findings deepen our comprehension of the interplay between yam starch and polyphenols, offering valuable insights for the development of novel food products with enhanced health benefits.