Studies on the Suitability for Storage of High Moisture Rough Rice : II. The cause of development of deteriorate rice on the high moisture rough rice in storage

Abstract

On the deterioration in the storage term of newly threshed fresh rough rice, the causes for the development of spotted rice and opaque rice were studied. 1. In the case of mixing storage of newly threshed rough rice and panicles in high moisture, the former developed many spotted grains but the latter did not. Consquently, the development of spotted rice related directly with the threshing process. (Table 1) 2. The surface of the brown rice from the newly threshed paddy suffered much mechanical damage by the threshing teeth, and in the majority of these grains, the spot developed at the site and in the same form as the damaged point. (Table 2) 3. The matured panicles sterilized at the heading time and non-sterilized were threshed when they were fresh, and then stored in high moisture conditions. The former had fewer spotted grains than the latter, and there was mold development in the spotted parts of the grains. (Table 3, 4) 4. When the newly threshed rough rice was stored until heavily deteriorated, the percent of spotted rice was a little less than the percent of the mechanically damaged grain. (Table 6) 5. Therefore, the cause for the quantity of spotted rice is explained by the following three factors: the mechanical damage on the grain surface, the mold propagation and the moisture condition. 6. When the high moisture rough rice above 20% was stored for many days, the opaque grains developed slowly without mechanical damage to the grain surface or mold in the paddy. In the final period of storage, the dry matter weight of the grain decreased and some of these grains were infected with aspergillus. In cases when the more mechanically damaged grains were stored, they had more opaque grains than the non-damaged and the much less opaque rice appeared in low temperature (8°C) than in high (32°C) in storage. (Table 7, 8, 9)