Test meal preparation
A nonglutinous rice (brand name: Yumepirika) cultivated in Hokkaido, Japan was used a test meal in this study. The GABA rice was produced by an air heating and humidifying process developed by Mizuno et al.14 and 15 The temperature and humidity of grain were controlled using testing equipment (LGB03; Satake) scaled down of actual equipment to increase the quantity of GABA, and then the product (grain) was hulled and milled. The quantity of GABA was analyzed by the automatic amino acid analysis method, based on the procedure described by Ohisa et al16 but with some modifications. The production and the packing of rice were carried out at Satake Corporation in a quality-controlled manufacturing plant in compliance with the Food Sanitation Act (the Ministry of Health, Labor, and Welfare of Japan). The quality and safety of the test samples were thoroughly examined by Satake Co., Ltd.