Correlation among Whiteness, Amylose Content and Moisture Content of Low Amylose Rice Variety “Takitate”

The amylose content and whiteness of rice endosperm are affected by environmental conditions. Since the amylose content and endosperm whiteness of a low amylose variety "Takitate" varies from year to year, the quality stabilization is a matter of major concern. In this study, we examined the amylose content, whiteness and moisture content of 165 samples of "Takitate" rice cultivated on 10 districts in Miyagi prefecture in 2003. Because of the cool summer, the amylose content was 12%, which was higher than that in average year. A negative correlation between amylose content and whiteness was detected in the rice grains with a moisture content of ca. 15%, but in those with a moisture content of less than 14% the endosperm was not translucent but chalky regardless of its amylose content. Furthermore, a negative correlation was detected between moisture content and whiteness in the rice grains with the same amylose content. These results indicate that whiteness of rice is not only affected by amylose content but also by moisture content and that the variation of whiteness would be minimized by adjusting moisture content of rice grains.