Chinese yam (Dioscorea opposita Thunb.) starch-ferulic acid complexes: Preparation, characterization, and physicochemical properties.

Polyphenols are known to interact with starch to form the V-type inclusion complex or the noninclusive complex. It is hypothesized that the addition of polyphenols could improve the properties of Chinese yam (Dioscorea opposita Thunb.) starch, and the properties of the complexes could be regulated by controlling the additive amount of polyphenols. To test this hypothesis, the effect of varying ferulic acid (FA) concentrations (3%, 9%, and 15%) on the structural characterization and physicochemical properties of Chinese yam starch (CYS) was investigated. X-ray diffraction analysis showed that CYS complexes with FA generated characteristic peaks comparable to those of native CYS, but FA caused the crystal morphology of CYS to change from a B-type to V-type. During the gelatinization process, FA increased the solubility, water-holding capacity, and hardness of CYS complexes, which was possibly attributed to the CYS molecules reaggregating and the formation of ordered crystals. The transmittance of CYS complexes decreased from 12.21% to 7.46% when the FA concentration increased from 3% to 15%. In addition, FA increased the viscosity and elasticity of the CYS system but decreased retrogradation. Thus, FA improved the structure and properties of CYS complexes, which can provide new directions and ideas for the development of CYS-based food. PRACTICAL APPLICATION: This study showed that adding FA can affect the characterization and physicochemical properties of CYS. We expect that CYS-FA complexes can be used for health and medicine products thanks to unique nutritional values.