3.4. Low-pressure plasma increases GABA and TPC accumulation
during germination
The effect of low-pressure plasma on GABA accumulation during
germination was evaluated, and results are shown in Fig. 4.
The GABA content of unexposed brown rice was 7.5–19.7 mg/
100 g (dry weight basis) and increased significantly after germination.
After a 1- and 2-kV exposure, the higher GABA content was
evident from 0 to 18 h of germination, and there was no effect at
24 h of germination. For all germination periods, a 3-kV exposure
resulted in significant increases in GABA content (7.5–28.1 mg/
100 g) compared with unexposed brown rice.
The influence of low-pressure plasma on TPCs of germinated
brown rice is presented in Fig. 4. As germination time increased,
TPCs increased as well, similar to results reported by Maisont
and Narkrugsa (2010). The greatest increase in TPCs was 1.84 mg
GAE/g at a germination time of 24 h. TPCs of brown rice were not
influenced by low-pressure plasma. However, after plasma exposure,
brown rice showed a significant increase in TPCs at 18 and
24 h of germination, especially after a 2 or 3-kV exposure. The
maximum value of TPCs was about 2.30 mg gallic acid eq/g for a
3-kV exposure after 24 h of germination. Oxygen-argon plasma
also revealed the same effect that the contents of total phenolics
and GABA could be increased by plasma