Changes in Rice Grain Quality-Related Characters According to Storage Periods and Temperatures in Korean Rice Varieties.

During the harvest season, drying and storage facilities at Rice Processing Complexes (RPCs) are not enough to manage all the harvested rice, which causes quality deterioration and decomposition. Also, rice export is being limited due to the high cost of long-term storage of exported rice while shipping. This study was conducted to investigate the germination rate, fat acidity and lipoxygenase activity of brown rice after storage of 3, 6, 9 and 12 months at room temperature (25°C) and high temperature (35°C) with 22 Korean and 2 Japanese varieties. Germination rate of rough rice was decreased to 72% after storage of 9 months at 25°C and that of Donganbyeo, Mangeumbyeo, Boseogchal, Saenuri, Shindongjinbyeo, Jinbaek, Cheongmu, Pyeonganbyeo, Honong, Hopyeongbyeo and Hopum were below 72%, while Koshihikari, Onnuri, Hitomebore, Jinsumi, Jinmibyeo sdand Chilbo showed above 80% after storage of 12 months. In 35°C condition, germination rate was decreased to 35 and 33% after 3 and 6 months, respectively. Koshihikari, Hitomebore, Ilmibyeo, Jinsumi, Jinmibyeo and Chilbo maintained 80% or higher germination rate even after 6 months. Fat acidity was increased according to storage periods and increasing level was higher at 35°C than at 25°C. Lipoxygenase activity was decreased according to storage periods and decreasing level was higher at 35°C than at 25°C. Although the protein content was not significantly different according to the storage period at both 25 and 35°C, significant difference existed among cultivars. Amylose content was increased until 6 months at both 25 and 35°C, but decreased after 9 months. Fat acidity and protein content were negatively correlated with amylose content, while amylose content was positively correlated with lipoxygenase activity after 12 months at 25°C. Germination rate was negatively correlated with fat acidity and protein content, while fat acidity was positively correlated with protein content and negatively correlated with amylose content and lipoxygenase activity after 6 months at 35°C. 24 varieties were classified into 3 groups on the basis of germination rate, fat acidity and lipoxygenase activity after 12 months at 25°C and 6 months at 35°C. Group I including 8 varieties of Koshihikari, Onnuri, Chilbo, Jinsumi, Hitomebore, Jinmibyeo, Ilmibyeo and Hwashinbyeo showed higher germination rate, lower fat acidity than Group II including 11 varieties of Nampyeongbyeo, Chucheongbyeo, Dongjinchal, Donganbyeo, Mangeumbyeo, Cheongmu, Saenuri, Boramchan, Boseogchal, Shindongjinbyeo, Pyeonganbyeo, Honong and Jinbaek. Hopyeongbyeo and Hopum showed higher germination rate, lower fat acidity at 35°C than 25°C among 3 varieties belonging to Group III, while Hwanggeumnuri showed higher germination rate, lower fat acidity at 25°C than 35°C.