취반후 저온보온(63, 66, 69, $72^{circ}C$) 및 변온에 따른 쌀밥의 이화학적 특성을 측정하였다. 보온시간이 경과할수록 모든 시험구에서 고온성 세균이 증식하기 시작하여 6시간째부터 균수가 급속하게 증가하였고, 저온보온중 보온온도가 낮을수록 세균의 증식속도가 더 빨랐으며, 대체로 보온 18시간 부근에서 생균수가 최대로 되는 경향이었다. 또한 고온성 세균수가 보온 6시간때에 $10^6$ CFU/g이었던 것이 1차 열충격 후 보온 8시간째에는 $10^5$ CFU/g이하로 줄어들었으나, 그 이후에 점차 증가하였고, 이를 다시 보온 6시간 이후에 2차 열충격을 한 결과 24시간 보온 때까지 이취를 생성하는 것으로 추측되는 균수 이하로 고온성 균의 성장을 억제하여 이취의 생성을 방지할 수 있었다. 변온 보온중 수분함량은 $63^{circ}C$보온보다는 낮게 나타났으나, $72^{circ}C$보온보다는 높게 나타났고, 명도(L)는 변온보온시가 $72^{circ}C$보온시보다 높았고, $63^{circ}C$보다는 낮았으며, 황색도(b)는 명도와 반대경향이었다. 밥의 보온중 텍스쳐는 보온온도 및 변온에 따라 유의적인 변화는 없었으며, 관능검사에서 변온보온은 저온보온에 비하여 이취 발생 및 황변도가 억제되었으며, 조직감 및 종합적인 기호도가 더 좋게 평가되었다.
The changes in physicochemical properties of cooked rice stored in an electric rice cooker at different temperature (63, 66, 69 and $72^{circ}C$) were investigated. The growth of thermophilic bacteria was gradually increased in all samples with storage time up to 6 hours and increased rapidly afterward. The bacterial growth rate was higher during storage at low temperature than at high temperature, and the bacterial number generally reached the maximum at 18 hours of the storage. The number of bacteria in sample stored at $63^{circ}C$ was increased to $10^6$ CFU/g after storage for 6 hours. The heat treatment at 6 hours of storage decreased the bacterial number to $10^5 $ CFU/g at 8 hours of storage. Bacterial number was gradually increased with storage time after the first heat treatment. When the sample was reheated after 8 hours of storage, the bacterial number was reduced to the level at which off-odor was not detected after storage for 24 hours. During the storage, moisture content of heat-treated sample was lower than that of sample stored at $63^{circ}C$ but higher than that of sample stored at $72^{circ}C$. The L value of heat-treated sample was higher than that of the sample stored at $72^{circ}C$, but lower than that of the sample stored at $63^{circ}C$. The b value showed an opposite trend to the L value with regard to the storage temperature. Changes in texture were not remarkable during the storage for the sample heat-treated and stored at low temperature. The occurrence of off-odor and browning was depressed in the heat-treated sample, and the texture and overall eating quality were more acceptable than the samples stored at low temperature.
