Rheological Properties of Rehydrated Freeze Dried Instant Rice

동결건조 즉석미반의 리올로지적 성질

Rheological properties of rehydrated freeze dried instant rice were investigated in comparison with that of cooked rice. The time changes in reciprocal hardness of instant rice grains at various rehydration temperatures$(60{\sim}90^{\circ}C)$ could be expressed by the first order reaction rate equation regardless of rehydration temperature and reaction rate constant increased as the rehydration temperature increased. Activation energy for rehydrating instant rice was 6.1 kcal/g-mol. Analysis of compressive stress relaxation test showed that the viscoelastic properties of both rehydrated instant rice and cooked rice grains could be expressed by 6-elements generalized Maxwell model. Rehydrated instant rice revealed higher relaxation decay than that of cooked rice and showed the elastic property increased by increasing the rehydration temperature.

재수화한 동결건조 즉석미반의 리올로지 성질을 통상법으로 취반한 미반과 비교하면서 조사하였다. 온도$(60{\sim}90^{\circ}C)$를 달리한 복원시간에 따른 미립 경도의 역수(연화도)는 복원온도에 상관없이 1차 반응 속도식에 따라 감소하였고, 경도반응의 속도 상수 값은 온도에 따라 증가하였으며, 이의 활성화 에너지는 6.1 kcal/g-mol이었다. 여러 온도 $(60{\sim}90^{\circ}C)$에서 복원시킨 즉석미반의 압축응력 완화 곡선은 통상법으로 취반한 미반과 마찬가지로 일반화된 Maxwell의 6요소 역학모형으로 설명되었고, 즉석미반은 취반미보다 완화되기 쉬우나 복원온도가 높을수록 탄력성이 높아지는 특성을 나타내었다.