The application of image analysis to valuation on white-core in kernel of rice for sake brewery

Abstract

It is expected by rice breeders and sake brewers to establish the simple means for evaluating the size of white-core in grains of rice for sake brewing. In this study, we measured the white core of each grain in two cultivers, Ipponjime and Gohyakumangoku, by using the image analysis. The results showed that the relative size of white core to the whole size of grain, i.e. white-core rate, varied widely from grain to grain (0 ~ 100 %) in the same cultiver. Although the average of white-core rate in Ipponjime seemed to be larger than that in Gohyakumangoku, there was no significant difference between them. But the region where the white core was expressed in grains was different between two cultivars. Then we divided a grain in four parts, i.e. the 1 st, 2 nd, 3 rd and 4 th quadrants, and examined relative size of white-core in each quadrant. The results showed that, in Gohyakumangoku, the white core was expressed mostly in the 1 st and 2 nd quadrant, but in all quadrants in Ipponjime. Based on the findings, we made the standard image of grains which have variable size of white-core by superimposing the image of 85 grains in each cultiver.