Correlation of Antioxidant Activity and Phytochemical Profile in Brown Rice and Brown Rice Products

Abstract

Brown rice and brown rice products (brown rice, germinated brown rice, dry
germinated brown rice, germinated brown rice noodle and dry germinated brown
rice noodle) were studied for their total phenolic, total flavonoid, γ-aminobutyric
acid (GABA) content and antioxidant activity by DPPH and FRAP assay. The results
indicate that the brown rice extract shows the highest on total phenolic contents
(0.52±0.03 mg GAE/g of fresh weight), followed by germinated brown rice,
germinated brown rice noodle, and dry germinated brown rice noodle, respectively.
The total flavonoid content is only found in brown rice (0.35±0.03 mg quercetin/100
g sample). In GABA content, the germinate brown rice shows the highest on GABA
value (75.02±0.52 mg GABA/g of fresh weight), followed by germinate brown rice
noodle, dry germinate brown rice noodle, and brown rice, respectively. Percentage
of inhibition and the concentration of sample required for 50% scavenging of the
DPPH free radical (IC50) were determined for the antioxidant activity, germinated
brown rice shows the highest DPPH (IC50; 27.2±4.3 mg/mL), followed by brown
rice, and dry germinated brown rice, respectively. Brown rice shows the highest
FRAP (5.95±8.44 mM Fe (II) /g of fresh weight), followed by germinate brown rice,
germinate brown rice noodle, and dry germinate brown rice noodle, respectively.