Abstract
Rice grains contain starch degrading enzymes, including α-glucosidases, α-amylases, β-amylases, pullulanase and isoamylases. To investigate the elution behavior of these enzymes from rice grains into cooking water during rice cooking, we separated cooking water from rice grains after soaking (20°C) and when the temperature reached 40°C and 60°C during cooking. Immunological detection of these enzymes in rice grains and cooking water was carried out with SDS-PAGE and immunoblot. Bands corresponding to pullulanase, α-glucosidase, isoamylase 1, and α-amylase E were detected in both rice grains and cooking water at each temperature. Bands corresponding to α-amylases A + B and H were not detected in rice grains, but were detected in the cooking water at each temperature. The β-amylase band was detected in rice grains but was not detected in cooking water. These results suggest that the amount of enzyme eluted into cooking water depends on enzyme localization and quantity in rice grains.
