<研究報告>炊飯過程における部位的変化について(第4報) : 自動電気炊飯器

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Experiments were done on rice cooked by two types of home automatic electric cookers, National SR-10FH (directly heating type) and Toshiba RC-103 (indirectly heatingtype), in order to see whether the same positional differences in taste could be found as those observed in the previous reports, in which an automatic gas one-step switch-off cooker, Rinnal 5-A had been used. Sensory tests were carried out with rice at the upper periphery, center part and center of a bottom of the cookers. Objective tests were also carried out with rice at the abovementioned parts at the times of apparent boiling, switch-off and the end of cooking. Results obtained are as follows. Sensory tests: The scoring tests revealed that rice at the center part of the directly heating cooker and at the upper periphery of the indirectly heating cooker was more tasty than that at the center of a bottom of the cookers of both types at the 0.1% level of significance. The differences in taste among the different parts were greater in the indirectly heating cooker than in the directly heating one. Objective tests: 1. Water content: In both the directly and indirectly heating cookers, the content increased from the time of switch-on to switch-off, then showed a slight decrease until the end of cooking. The difference in the content appeared at the time of boiling, and the content was the highest at the center of a bottom in the two types of the cookers. The lowest values were obtained at the center part of the directly heating cooker and at the upper periphery of the indirectly heating one. These states persisted until the end of cooking. The differences in the water content among the different parts were larger in the indirectly heating cooker than in the directly heating one. 2. Ratio of the increase in volume: The ratios increased from the time of switch-on to that of switch-off, and decreased until the end of cooking, in both types of the cookers. The differences in the ratios among the different parts could be detected at the time of boiling, and the ratios was the largest at the center of a bottom in the two types of the cookers. The lowest values were obtained for the center part of the directly heating cooker and for the upper periphery of the indirectly heating one. These trends did not change until the end of cooking. The range of the partial differences was larger in the cooker of the indirectly heating type than in that of the directly heating one. 3. Rate of dehydration In the two types of the cookers, dehydration proceeded at gradually decreasing rates between the time of boiling and the end of cooking. At the time of switch-off, the rate of dehydration was slightly higher at the center of a bottom, and the rates at the upper periphery and at the center part were the lowest and intermediate, respectively, in both the directly and indirectly heating cookers. These differences lasted until the end of cooking. The range of the differences were wider in the indirectly heating cooker than in the directly heating one. 4. Visco-elasticity: In both types of the cookers, the firmness and elasticity somewhat declined from the time of switch-off to the end of cooking, while the viscosity increased. In the directly heating cooker, the center part of a bottom, the center part and the upper periphery showed always the highest, the lowest and intermediate values, respectively. The trends in the indirectly heating cooker were similar to those in the directly heating one, but seemed to be complicated. 5. "Cells" of the grain: Observations of the corss sections revealed that the grain had a half-boiled part at its center at the time of boiling in the two types of the cookers. The half-boiled part, however, disappeared by the time of switch-off, and the grain swelled abruptly. Further swelling took place at the end of cooking. The grain seemed to be somewhat smaller at the center part in the directly heating cooker and at the upper periphery in the indirectly heating co
福岡女子大学の論文
1981-01-20

<研究報告>炊飯過程における部位的変化について(第4報) : 自動電気炊飯器

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