Effect of mechanical activation on physico-chemical properties and structure of cassava starch

Cassava starch was mechanically activated with a stirring ball mill and subsequently studied for cold-water solubility and theological characteristics. In addition, the crystal structure, thermal properties, functional groups, granular morphology and size distribution of the activated cassava starch were further characterized using granularity analysis, scanning electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy and differential scanning calorimetry. It was found that the crystal structure and granular morphology of cassava starch were significantly altered. Specifically, the crystalline structure of the cassava starch was significantly degraded, and the resulting amorphous particles were seen to agglomerate during the process of mechanical activation. Also, the gelatinization temperature and enthalpy, apparent viscosity and shear thinning of cassava starch were reduced, resulting in enhancement of cold-water solubility of the starch. Infrared spectroscopy showed no new functional groups produced during the mechanical activation process. (c) 2006 Elsevier Ltd. All rights reserved.