Development of Long-term Rice Storage Techniques for Preserving High Quality at a Temperature below Ice Point

研究了一种利用新鲜冷冰冰的空气在冰点以下储藏大米的新技术。研究了不同含水量的水稻在不同冻结温度下的冻害程度，以及在4年的储藏期内，冰点以下的温度对水稻生理特性的影响。水分含量低于17.8%的大米即使在-80 ℃的温度下也不会结冰。低温能保持稻米的活力，减少稻米的生理活性和淀粉劣变，保持稻米品质。从1999年11月底开始，1000吨糙米储存在两个筒仓中，并在2000年1月使用新鲜的冷冰冰的空气从每个筒仓的底部到顶部进行通风。糙米温度降到冰点以下。2000年7月底，每个筒仓中心的糙米温度仍在冰点以下。储存在筒仓中的大米质量保持在与新鲜收获的大米相似的水平。将大米储存在冰点以下并利用新鲜的冷冰冰的空气，可以在不需要冷却装置或电力的情况下保持高水平的大米质量。在农场试验之后，这种贮藏技术在寒冷地区的使用越来越多。在日本最北端的岛屿北海道，自1996年以来，已经建造了26个谷物升降机。2003年底稻谷储藏量为11.5万吨。

A new technique for storing rice at a temperature below ice point using fresh chilly air was developed. Freezing temperatures and extents of freezing injury of rice with various levels of moisture content were studied, and effects of temperature below ice point during a four-year storage period on the physiological properties of rice were investigated. Rice with moisture content of less than 17.8% did not freeze even at a temperature of-80° C. Low temperature maintained the vitality of rice, minimized physiological activities and starch deterioration in rice, and preserved rice quality. One thousand tons of rough rice was stored in two silos from the end of November 1999 and was aerated from the bottom to top of each silo using fresh chilly air in January 2000. The rough rice temperature fell below ice point. At the end of July 2000, the rough rice temperature in the center of each silo was still below ice point. The rice quality stored in the silos was preserved at a level similar to that of freshly harvested rice. A combination of rice storage below ice point and utilization of fresh chilly air enables the rice quality to be preserved at a high level without the requirement of a cooling unit or electricity. The use of this storage technique has been increasing in cold regions after the on-farm experiment. In Hokkaido, the northernmost island in Japan, 26 grain-elevators have been constructed since 1996. The storage capacity of rough rice was 115,000t at the end of 2003.