3.5. Low-pressure plasma increases antioxidant capacity of
germinated brown rice
Antioxidant capacity can be measured by ABTS and DPPH radical
scavenging activity. Both germination time and low-pressure
plasma altered the antioxidant capacity as shown in Fig. 5. Both
assessment methods revealed changes during germination, with
antioxidant capacity increasing continuously with germination
time. The antioxidant capacity of germinated brown rice ranged
from 6.71 to 7.75 mg Trolox eq/g and 11.9 to 15.4 mg Trolox eq/g
for ABTS and DPPH radicals, respectively. The data from both
assessment methods indicated that low-pressure plasma result in
the increase of the antioxidant capacity of brown rice. In combination
with germination time, the antioxidant capacity of brown rice
increased markedly. The maximum antioxidant capacity was evident
for a 3-kV exposure after a 24 h germination time, and the
values were about 10.54 and 20.6 mg Trolox eq/g for ABTS and
DPPH radical scavenging activities, respectively.
Exposure to low-pressure plasma stimulates the germination of
brown rice, which was verified by increases in germination percentage,
seedling length, and a-amylase activity (Figs. 1 and 3).
Accompanying increased germination, TPCs and GABA in germinated
brown rice increased significantly (Fig. 4). Thus, the higher
antioxidant capacity of germinated brown rice after exposure to
plasma was due to the increases in these biological compounds