Germinated brown rice is a well-known functional food due to its high content of gammaaminobutyric
acid (GABA). This study was designed to test the difference of producing GABA
in two domesticated rice genotypes (indica and japonica rice), and the effects of adding exogenous
glutamic acid or gibberellin, and processing conditions. Soaking at 30 °C and germination
at 35 °C during 36 h resulted in the highest GABA in distilled soaking water with
pH 7. The indica rice showed higher GABA levels than japonica rice. GABA was increased
under acidic soaking conditions or by adding L-glutamic acid (L-Glu) at the optimal concentration
of 1.0 g L−1 and gibberellin A3 (GA3) at the optimal concentration of 0.25 mg L−1.
The lower accumulation of GABA in japonica rice could be remedied by adding exogenous
L-Glu and GA3, and providing acidic soaking conditions.The results help to efficiently produce
GABA enriched functional food.