Structure, properties and potential applications of phytoglycogen and waxy starch subjected to carboxymethylation.

The structure and properties of phytoglycogen (PG) and waxy starch (WS) from different mutants subjected to carboxymethylation (CM) were investigated. FT-IR analysis confirmed the carboxymethylation of PG and WS. The degree of substitution (DS) increased with increasing of the ratio of monochloroacetic acid to anhydroglucose unit, while DS of CM-PG was higher than that of CM-WS using equivalent modification conditions. The weight-average molecular weight (Mw) and radius of gyration (Rz) of CM-WS increased with the DS, whereas the Mw increased and Rz was nearly constant for CM-PG. The zeta-potential of CM-WS reduced and the viscosity increased significantly as DS increased, while the viscosity of CM-PG was remarkably lower than that of CM-WS with equivalent of DS. The increase of DS in CM-starches resulted in a substantial reduction of RDS accompanied by the increase of SDS and RS. The results revealed the promising application of CM-PG as a potential carrier system for bioactive ingredients.