c-Aminobutyric acid (GABA) is a non-protein amino acid widely
found in eukaryotes and prokaryotes. It is known as one of the
main inhibitory neurotransmitters in the sympathetic nervous system
and plays an important role in cardiovascular functions
(Wang, Tsai, Lin, & Ou, 2006). The changes in the GABA content
during germination and HPT are shown in Fig. 1. In the control
experiment (HP0), GABA content increased from 25.76 mg/100 g
in raw rough rice to 87.88 mg/100 g after 4 days of germination
and decreased to 74.62 and 57.95 mg/100 g after 5 and 6 days of
germination, respectively. These results are similar to those
reported by Moongngarm and Saetung (2010). Kim, Hwang, et al.
(2012), which showed that the GABA content of different parts of
rough rice was increased by germination. The GABA content is
related to protease and glutamate decarboxylase (GAD) activity.
Amino acids are stored in rice grains as storage proteins that are
decomposed by hydrolysis during germination and converted into
transportable amides, and supplied to the growing rice seedlings.
Water absorption during soaking and germination activates GAD
enzymes (Komatsuzaki et al., 2007) and results in the conversion
of glutamic acid to GABA. The GABA content of germinated rough