Effect of Grain Thickness on Appearance and Cooked Rice Quality of Paddy Rice Variety “Hitomebore” and Effect of Temperature at Ripening Stage

Abstract

The effect of brown rice grain thickness on the appearance quality and physical properties of cooked rice were investigated using rice variety ‘Hitomebore’, brown rice with a thickness of more than 1.9 mm, the conventional sieve and with four different thicknesses (1.9-2.0, 2.0-2.1, 2.1-2.2, and more than 2.2 mm). In addition, the effects of ripening temperature on the appearance quality and physical property of cooked were analyzed. In addition, the physical properties of cooked rice with a thickness of 1.9-2.2 mm tended to be hard, but the overall balance was higher than that of ‘Hitomebore’ on the conventional sieve. Brown rice with a thickness of 2.1-2.2 mm showed the highest ratio of lowered appearance quality due to the high temperature in the early ripening stage; and, the amylose content and the stickiness and balance of cooked rice of 2.1-2.2 mm grains decreased due to the rise in temperature in the late stage of rice ripening. ‘Hitomebore’ with a thickness of more than 1.9 mm used in this study had good appearance quality and physical properties of cooked rice, However, the quality of ‘Hitomebore’ on the conventional sieve might be susceptible to the effect of high temperature during the ripening period, affected by the susceptibility of grains with a thickness of 2.1-2.2 mm.