2006 Volume 8 Issue 1 Pages 1-7
In order to identify the index traits for evaluating the deterioration of palatability of stored rice grains, we analyzed the varietal differences in the deterioration of palatability associated with one-year storage treatment at room temperature among 19 cultivars with a high grain palatability in 1998 and 1999. The grain palatability of each variety when newly harvested showed a positive correlation with that under storage conditions. Cluster analysis was performed to detect the varietal differences in the deterioration of palatability. Nineteen cultivars were classified into five groups by the grain palatability values when newly harvested and under storage conditions. Group1 : cultivars with a grain palatability almost equivalent to that of Koshihikari. Group2 : cultivars with a superior grain palatability to that of Koshihikari. Group3 : cultivars with a slightly inferior grain palatability to that of Koshihikari. Group4 : cultivars which showed an almost equivalent grain palatability to that of Koshihikari when newly harvested and showed an inferior grain palatability to that of Koshihikari under storage conditions. Group5 : cultivars with an obvious inferior grain palatability to that of Koshihikari. It was concluded that the Group4 cultivars showed a significantly larger deterioration of grain palatability than the Group1 cultivars including Koshihikari. We investigated the relationship between the grain palatability values and physicochemical properties in the newly harvested materials and those under storage conditions, and showed that the Hardness/adhesiveness ratio (H/A3) and the Hardness/adhesion ratio (H/−H) for textural characteristics had increased along with the deterioration of palatability after the storage treatment. Therefore, these textural characteristics were useful for evaluating the deterioration of palatability of rice grains after storage. We conducted a viviparity test in the facilities under high temperature and high humidity conditions, and observed that the Group4 cultivars (higher deterioration of grain palatability) showed a significantly higher level of viviparity than the Group1 cultivars (lower deterioration of grain palatability). It was thus suggested that there might be some relationship between palatability and viviparity.
