Hierarchical structure and physicochemical properties of highland barley starch following heat moisture treatment

Herein, we concern the multi-scale structure and properties (digestibility and pasting) of highland barley starch following heat moisture treatment (HMT). With the moisture content (MC) rose, HMT reduced the molecular weight (molar mass) but increased the amylose content and the V-type polymorph. When the MC was lower than 25%, a higher MC resulted in increases in the long- (crystallites) and short-range orders (double helices, etc.); nonetheless, a further elevated MC (i.e., 30%) tended to reduce the amounts of these ordered structures. Also, the SAXS results reveal that the lamellar structure could be gradually vanished by the increased MC. These structural changes on multiple scales transformed part of rapidly digestible starch into the slowly digestible and/or resistant forms, accompanied by higher pasting temperature and lower paste viscosity. Hence, highland barley starch following HMT can serve as a food ingredient with reduced digestion rate and paste viscosity.