Abstract

Starches from various botanical origins (rice, maize and potato starches) were cross-linked in the presence of epichlorohydrin (EPI), respectively. Then, the cross-linked starches were further oxidized with sodium hypochlorite (NaOCl, 2.5% w/w) to obtain oxidized cross-linked starches (OCS). The chemically modified methods on the physicochemical properties of different starches were investigated. It was found that cross-linking treatment increased peak, setback and final viscosities of rice and maize starches but decreased those of potato starch. The paste clarities of cross-linked rice and maize starches significantly reduced, whereas those of cross-linked potato starch increased. Oxidation treatment significantly decreased peak, final and setback viscosity values of all starches and significantly increased paste clarities. Dual-modified starches had higher peak, final viscosities and the ability to resistant to shear compared with oxidized starches, meantime it had lower tendency of retrogradation and higher paste clarities compared with cross-linked starches. Under those conditions of dual-modification, undesirable starch properties were counteracted.

Key words: Rice, maize, potato, starch, cross-linking, oxidation, oxidized cross-linking.