SCREENING OF BROWN RICE VARIETIES AND OPTIMIZATION OF GERMINATION CONDITIONS FOR HIGH gamma-AMINOBUTYRIC ACID YIELD

One of the important active components in germinated brown rice (GBR) is gamma-amino-butyric acid (GABA), which may lower blood pressure and has anti-depression effects. This study aimed to improve the GABA yield of GBR, and to investigate GABA-rich germinated brown rice in terms of rice variety screening and optimization of germination conditions. After the screening process, the six varieties with the highest GABA yields in GBR were identified as 1D67, 1D117, 1D31, N84, 1D71 and 1D70 with GABA contents (mg/ml) of 29.12, 26.49, 26.09, 24.82, 23.80, and 22.84, respectively. The GABA yield of GBR under optimal germination conditions determined by both a single factor optimization and an orthogonal test design was 28.94 mg/100 g, 16.6% higher than before germination condition optimization. Results of a range analysis showed that the order of significance for five factors affecting GABA yield of N84 germinated brown rice were as follows: germination temperature > soaking liquid pH > soaking time > soaking temperature > germination time. The optimal germination conditions for producing GABA-rich germinated brown rice were soaking solution pH 4.7, soaking 9 hrs at 20 degrees C, then germination 34 hrs at 39 degrees C.