Effect of Storage in Frozen Soil on the Quality of Adzuki Beans [<i>Vigna angularis</i> (Willd.) Ohwi et H. Ohashi], Soybean [<i>Glycine max</i> (L.) Merr.], Red Kidney Beans [<i>Phaseolus vulgaris</i> L.], and Buckwheat [<i>Fagopyrum esculentum</i> Moench

Abstract

Ice and snow, which are important components of Earth’s climate system, maintain high humidity and low temperature, and hence can be used to preserve the quality of agricultural products. The purpose of this study was to investigate how the quality of adzuki beans, soybean, red kidney beans, and buckwheat was affected after storage in frozen soil for 15 months. Storage of the grains in frozen soil, in a sealed polyethylene bag, helped in controlling humidity and maintaining a low temperature during the storage period, thus suppressing the increase in the fatty acid values and thiobarbituric acid reactive substances. The fatty acid value was not the sole criterion for evaluating the quality when the moisture content of the grains was too low. Moisture contents of 12.5–13.5%, 9–11.5%, 11–13%, and <14%, combined with low-temperature conditions, were best suited for storing adzuki beans, soybean, red kidney beans, and buckwheat, respectively. Hence, storage of Hokkaido’s main agricultural products in frozen soil, in a sealed polyethylene bag, is expected to have promising applications in the storage industry.