Controlling degradation of low-molecular-weight natural polymer dextrin using gamma irradiation

Dextrin, which is widely used throughout many industries for their functional properties, was selected for studying the influences of gamma irradiation on its viscosity, physicochemical properties and dextrin granule structure. The formation of radicals during irradiation process of dextrin in air condition was investigated by electron spin resonance (ESR) showing the influence of irradiation and storage parameters on the nature and concentration of the free radicals. Two major radicals or groups of radicals are observed. The radicals show g-values varying among g=2.0102 +/- 0.0002 and g=2.0126 +/- 0.0006. Irradiation was observed to induce increases in the intensity of single. The material left behind after irradiation treatment was characterized using thermal analysis, TGA and DSC. A structural analysis was made using SEM and X-ray diffraction to investigate whether the partial hydrolysis had any influence on the granular structure and the crystallinity of the dextrin. The results show that dextrin undergoes oxidative degradation under the influence of gamma radiation. (C) 2008 Elsevier B.V. All rights reserved.