해조류 첨가가 쌀코지 제조와 효소활성에 미치는 영향

This study investigated the effects of selected seaweeds on rice koji preparation (rice inoculated with Aspergillus luchuensis) and enzyme activity. Four types of rice koji were prepared using one of three seaweeds (0.5% laver, 0.5% kelp and 0.5% green laver) or a control for 72 h. The changes in the moisture content, water activity, pH, total mold cell count, amylase and protease activities were measured. During preparation, there was no significant difference in the moisture content among the four kojis, whereas the pH in the kojis made with either laver or green laver decreased rapidly compared with the control (P<0.05). This seemed to result from the seaweeds promoting the growth of mold cells. In terms of the activities of both amylase and protease, the koji with laver was superior. Subsequently, the amylase and protease activities of the koji made with laver were evaluated at various pHs (3 to 9), temperatures (15-55℃) and NaCl concentrations (0-10%). The activities of both enzymes decreased notably at pH 9 and the protease activity decreased at temperatures above 45℃. Although the activities of both enzymes decreased at greater than 2.5% NaCl, activity was present at 10% NaCl.