“Bikkuridaki” method for cooking brown rice by adding water during cooking process: Examination of water addition conditions

Abstract

This study sought to scientifically characterize a traditional Japanese method of cooking brown rice, wherein the cooking liquid is depleted once after heating begins, followed by fresh water addition with continuous heating. The timing and amount of water addition were measured and it was determined that starting with a water-to-rice ratio of 1.2 and adding water at a ratio of 1.5 when the cooking liquid was depleted 10 minutes post-boil, followed by continuous heating for another 20 minutes, resulted in the highest quality and taste ratings of the rice. The optimal timing for water addition, when starch gelatinization reached approximately 60 %, significantly enhanced the taste of brown rice by optimizing water utilization. Additionally, the browning index, which reflects the degree of pericarp and seed coat rupture in cooked rice, correlated with water absorption and rice hardness, suggesting its utility as an index for assessing brown rice quality.