Cross-hierarchical analysis of self-assembly dynamics in enzyme-treated rice gel during retrogradation

The purpose of this study was to elucidate the self-assembly dynamics of rice gel and their influence on the physical properties of enzyme-treated rice starch during storage using a cross-hierarchical analytical approach. Two enzymes, α-glucosidase (AG) and branching enzyme (BE), were used in this study. Changes in the physical properties of rice gel during storage showed that, compared to the control, the increase in G′ and G″ for AG-treated gels was lower during storage, and that the change in tanδ of AG-treated gels was lower at 0.1 Hz. Small angle X-ray scattering and ultra-small angle X-ray scattering analyses revealed that the radius of gyration of the primary aggregates was not affected by enzyme treatment, but that the rate of increase in the radius of gyration of secondary aggregates was faster in both enzyme-treated gels. Atomic force microscopy revealed that AG treatment changed the shape of the extended clusters, while BE treatment changed the connecting structure of the extended clusters. The results showed that AG and BE treatment affected the mesoscale intermolecular and intramolecular self-assembly dynamics of rice gel, causing changes in its physical properties. [Display omitted] •The increase in G′ and G″ for enzyme-treated gels was lower during storage than enzyme non-treatment gel.•The aggregate growth behavior during storage of enzyme-treated rice gels was different depending on the hierarchy.•Enzyme treatment changed the morphology of amylopectin molecules.•Enzyme treatment affected the mesoscale intermolecular and intramolecular self-assembly dynamics of rice gel.