Abstract
Two kinds of cross-linked starch were prepared from corn starch by treatment with epichlorohydrin, and they were then extrusion-cooked. Some properties of the extrudates were investigated by scanning electron microscopy, X-ray diffractmetry and differential scanning calorimetry (DSC). The cross-linked starches exhibited the crystalline structures and some thermal transition, however, they did not increase their viscosities in amylograms. The cross-linked starches could be perfectly molten by extrusion cooking and solidified immediatly after extrusion. The cross-linked starch treated with epichlorohydrin of 3% to corn starch in weight (3% cross-linked starch) was most stably extruded under the following conditions: added water, 20%; die temperature, 150-160°C; and die pressure, 32-36 kg/cm2. The 3% cross-linked starch extrudate showed a flat X-ray diffraction pattern unlike the corn starch extrudate. The measurement of DSC clarified that all of extrudates showed almost no thermal transition or retrogradation. The solubility of the extrudate was negligible. It was thus concluded that an insoluble molten starch material could be prepared by extruding epichlorohydrin-cross-linked starch.
