초록
백미를 $4{\sim}30^{\circ}C$에서 3개월 저장하는 동안 수분흡수 속도 상수값과 부피증가 속도 상수값은 저장기간이 길어짐에따라 직선적으로 감소하였으며, 그 정도는 저장온도가 높을수록 현저하였고, 동일 온도에서는 부피증가 속도 상수값의 감소 정도가 컸다. 수분흡수의 활성화 에너지는 저장온도 $25^{\circ}C$를 전후하여 달랐고, 저장온도 $4{\sim}25^{\circ}C$에서는 저장 1.5개월까지, 저장온도 $25{\sim}30^{\circ}C$에서는 저장 2개월까지 크게 증가하였고 그 후에는 증가폭이 원만하였다. 쌀알의 경도는 저장 중 저장온도가 높을수록 더욱 증가하였다. 취반 속도 상수값은 저장시간의 경과에 직선적으로 감소하였으며 $4^{\circ}C$에서 보다 $20^{\circ}C$ 저장에서 크게 감소하였고, $20^{\circ}C$ 이상에서는 감소율이 크지 않았다. 취반의 활성화 에너지값도 저장기간의 경과에 따라 증가하였으며 저장 1.5개월에서 가장 크게 증가하였다. $4^{\circ}C$에 저장한 쌀은 색도의 변화가 없었으나 $20^{\circ}C$ 이상에서는 b(황색도)값이 증가하였다. 쌀가루의 아밀로그라프에 의한 최고점도는 저장시간과 온도가 높아짐에 따라 증가하였고, 시차주사열량계로 측정한 호화 엔탈피는 감소하였다.
The changes in water uptake rate, cooking property, color of rice grain, gelatinization property of milled rice during storage were studied. The water uptake rate constant of milled rice during storage at $4{\sim}30^{\circ}C$ for 3 months decreased, which was more pronounced at elevated storage temperatures. The activation energy of water uptake was different below and above $25^{\circ}C$ of storage temperature. The activation energy after storage for 3 months below and above $25^{\circ}C$ was 608 and 1269 cal/mole, respectively. The rice grain became harder and the cooking time was prolonged by $3{\sim}8$ minutes upon storage. The cooking rate constant was linearly decreased as a function of storage time. The activation energy of cooking after 1 month of storage was 235 cal/mole, which was increased by 1.7 times after storage of 1.5 months and thereafter by 1.2 times with the increase of 0.5 month. There were no significant changes in color of milled rice grains during storage at $4^{\circ}C$, but the increase of b value was observed at higher temperatures. The Initial pasting temperature of rice flour remained essentially unchanged during storage, but the peak viscosity consistently increased with the increase of storage time and temperature. The gelatinization temperature of rice flour by differential scanning calorimetry was not changed but enthalpy of gelatinization was decreased during storage.
(Department of Food Science and Nutrition, Dankook University)
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