Sample extraction
After germination for rough rice, the husks of
grains were removed before extraction. The extraction
for each sample was performed in duplicate. The
method of Jang and Xu (2009) with slight modification
was used for extraction step. Briefly, one gram of
each sample was transferred into a test tube (25 x 150
mm) to which methanol (3 mL) was added, and the
mixture was vortex mixed for 30 sec. The test tubes
were capped and placed in a 60°C water bath for 20
min. These test tubes were vortex mixed twice during
the incubation. Then, the methanol layer in each tube
was separated by centrifugation at 10,000 rpm for
10 min. The solvent supernatant was transferred to
a 10 mL volumetric flask. The residue was again
mixed with 3 mL of methanol. The supernatant was
separated as previously described and combined
with the previous supernatant. The tube containing
supernatant was adjusted to 10 mL. The extracted
solution was kept in 0°C until analysis.