Structure and physicochemical properties of native starch and resistant starch in Chinese yam (Dioscorea opposita Thunb.)

The physicochemical properties of starch in Chinese yam (Dioscorea opposita Thunb.) are highly dependent on the growth stage. However, relevant information available is limited. In this work, native starch and resistant starch (RS) were prepared from Chinese yam tuber at expansion stage and dormant stage, respectively. Their structural and physicochemical properties were determined. They presented A-type polymorphic structure. The starches from dormant stage had smaller granule sizes, lower amylose contents, less branching degrees of amylopectin, and higher proportions of double helix than those from expansion stage. Dormant stage induced starch to form a more compact structure with a higher crystallinity and larger amount of short-range ordering than expansion stage. Moreover, the starch paste from dormant stage had a high thermal stability. These results were helpful for further application of Chinese yam starch in food products.