Characterization of multi-scale structure and physicochemical properties of starch from diverse Japonica waxy rice cultivars

Eight Japonica glutinous rice cultivars, collected from seven different provinces in China, were selected to explore the structural and physicochemical properties of their starch. The apparent amylose content ranged from 0.07% to 1.5%. Of parameters related to molecular structure, aggregation (crystalline, short-range order and lamellar structure) and granule structure, the amylopectin A chain (DP 6–12) and B2 chain (DP 25–36), the crystallinity and the average repeat distance of lamella of the starch granule are important in influencing physicochemical properties of waxy rice starch. The A chain level of amylopectin in waxy rice starch was negatively correlated with the onset temperature, gelatinization enthalpy and setback viscosity, but positively correlated with α-amylase hydrolysis coefficient. However, the B2 chain level of the amylopectin and the crystallinity of waxy rice starch had opposite effects on these parameters. Also, higher percentage of A was correlated with less order of the lamellar structure of waxy rice starch. Waxy rice starch with smaller granule size was more easily hydrolyzed by α-amylase. The difference in multi-scale structure and physicochemical properties can contribute to the variation in the development of waxy rice starch starch-based products.