Physicochemical Properties, Structural and In Vitro Digestibility of Starch from Five Different Sources

Starch is one of the main sources of carbon water in food, the digestion rates of starches in food directly affects the concentration of glucose in the body. There are few comparative studies on the structures and digestibility starches from different sources. In this study, the molecular composition, physicochemical properties, crystal structure and digestion characteristics of five different sources of starches from purple yam (Dioscorea alata L.), iron stick yam (Dioscorea opposita Thunb. Cv. Tiegun) (DTT), potato (Solanum tuberosum L.), wheat (Triticum aestivum L.) and pea (Pisum sativum L.) were analyzed. The results showed that the content of resistant starches in DTT and purple yam were 84.1 and 73%, respectively, much higher than that of starches in potato (57.87%), pea (47.6%) and wheat (46.09%). The relative crystallinity of starch in purple yam was 45.5%, higher than the other four starches, in which that in wheat to be the lowest (33.1%). Starches in Purple yam and DTT contain more amylopectin medium chains and higher gelatinization temperature, while potato starch has the highest peak viscosity (PV). In general, purple yam and DTT starch have higher ordered chains and low digestibility, especially purple yam starch. The higher ordered chains is the main factor for the lower starch digestibility. This paper aims to reveal the relationship between starch structure and digestibility, and is expected to provide a reference for a better development and application of starch functional foods.