Multi-scale structure characterization of ozone oxidized waxy rice starch

The elucidation of multi-scale structural variation and oxidation reaction mechanism of ozone oxidized waxy rice starch molecules remains a big challenge, limiting its development of intensive processing. In the present work, the changes in the structure of waxy rice starch after ozone treatment were systematically researched by various characterization methods. The study has shown that with the increase in ozone oxidation time, the granules of oxidized starch were polygons with multiple face depressions. It was also observed that ozone first attacked the amorphous zone of the starch granules and then penetrated the crystalline zone. Combining 1D and 2D NMR (1H NMR, 13C NMR, HSQC and HMBC) and other methods, it was proved that ozone oxidation led to ring splitting between C2 and C3 of the glucose unit. The resulting hemiacetal groups showed different types of structures. Among them, the main structures were intramolecular acetals and intermolecular hemiacetals. This research offered theoretical guidance for the utilization of ozone oxidation technology for starch modification and the development of waxy rice new foods.