Physicochemical properties and microstructure of Chinese yam (Dioscorea opposita Thunb.) flour

Chinese yam has been widely used in food products. The growth stage significantly influences the qualities of Chinese yam. In this work, the physicochemical properties and microstructure of Chinese yam flours from expansion stage (ES-FF) and dormant stage (DS-FF) were investigated. The amylose content of DS-FF was lower than ES-FF, while the fat content of DS-FF was higher. The size and shape of Chinese yam flour granules at two growth stages remained consistently. ES-FF and DS-FF presented A- and C-type crystalline structure, respectively. DS-FF had a lower crystallinity and a higher short-range order than ES-FF. Dormant stage induced the formation of more amylose-lipid complex and ordered structure in granule. The values of To, Tp, Tc and enthalpy indicated that DS-FF had a higher thermal stability and a more compact structure than ES-FF. Moreover, Chinese yam flour showed a good elasticity and stickness with a high viscosity.