In Vitro Digestibility and Rheological Properties of Chinese Yam (Dioscorea opposita Thunb.) Starch Modified with Chlorogenic Acid

Chlorogenic acid (CA) has received extensive attention in the field of improving the properties of starch. At present, few studies have focused on the influences of chlorogenic acid (CA) addition levels on the physicochemical properties of Chinese yam (Dioscorea opposita Thunb.) starch (CYS). Therefore, the effects of varying chlorogenic acid (CA) concentrations (3%, 5%, and 7%) on the structural characteristics, in vitro digestibility, and rheological properties of Chinese yam starch (CYS) and its CA-incorporated complexes was investigated. The incorporation of CA disrupted the double-helix structure of starch, while promoting the formation of double- and single-helical structures in amylose, as revealed by Fourier-transform infrared spectroscopy and Raman spectroscopy, respectively. This led to decreased crystallinity and the formation of a V-type crystalline structure. The interactions between CA and CYS molecules facilitated the construction of a more compact network architecture within starch granules, thereby decreasing its in vitro digestibility and significantly increasing resistant starch content. Moreover, CA enhanced the short-range ordered structure of starch, restricted granule swelling, strengthened shear-thinning behavior, and reduced gel strength and viscosity. In summary, the complexation between Chinese yam starch and chlorogenic acid provides a promising strategy to tailor the rheological properties and in vitro digestibility of starch, providing a promising candidate substrate for fabricating low-digestibility starchy functional food formulations.