Abstract
The effect of micro-wave irradiation at 2, 450MHz on potato starch was studied. The irradiation was carried out on the starch in a closed test tube at various temperatures (final temperatures, 85-150°C) and at various moisture levels (moisture contents of starch, 5-25%).
In contrast to the treatment by conductive heating (heat-moisture treatment), which changes the “B” X-ray diffraction pattern of potato starch to the “A” pattern, the micro-wave heating does not cause such transition, but weakens the sharpness of the pattern showing the increase of amorphous region. The sharpness of B-crystalline peaks of the treated starches was partially recovered by steeping in water. On the other hand, the gelatinization properties of micro-wave irradiated starches were similar to those of the heat-moisture treated starch.
The susceptibility of starch to the amylases (α-amylase, glucoamylase) was found to be increased greatly by micro-wave irradiation in parallel with the increase of the adsorption capability to amylases.
