Approximately 100 mg of polished rice (5–7 grains) was washed twice with distilled water in a 15 mL test tube. After washing, 1.5 volumes of water (with respect to the dry weight of the rice grains) were added. Tubes were placed in 200 mL water and cooked using a normal program in a rice cooker (NS-WF10, Zojirushi, Japan).