Freezing as a method to maintain the quality of polished rice

Abstract

Polished rice was put into polyethylene bags, packed with Kraft paper, and preserved at four different temperatures : 10, -20, -40, and -60°C. Changes in quality of rice stored under these temperatures was tested at 2, 4, and 6 months using raw and cooked samples. In the case of preservation at 10°C, raw rice showed a decline in the rate of water absorption, higher hardness of the rice granules after water absorption, and a drastic decrease in the amount of reduced sugar eluted to the soaking solution, indicating deterioration in quality. Deterioration in quality was less at lower preservation temperatures ; rice preserved at -60°C showed little deterioration. Cooked rice samples using rice preserved at 10°C had higher hardness and lower adhesiveness, while cooked rice samples using rice preserved at -60°C showed little change in quality. After preservation for 6 months, cooked rice using the rice preserved at -60°C was significantly preferable to that using rice preserved at 10°C.