Abstract:
The antioxidant and antityrosinase activities were examined in germinated brown rice
of three indigenous Thai cultivars, namely Riceberry (purple), KDML 105 R-PSL-2 (red) and
KDML 105 (white), which are commonly grown in Buriram province of Thailand. Germination
was induced by steeping brown rice of each cultivar in distilled water (water: grain ratio = 2:1)
at ambient temperature for 6 h. After low temperature induction at 8 – 10 ºC for 24 h, the rice
kernels were allowed to germinate in a double-layered cotton cloth in the dark at ambient
temperature for 0, 24 and 48 h, in which the antioxidant and antityrosinase activities of
germinated brown rice were evaluated. The results revealed that germinated brown rice of all
studied cultivars appeared to display higher levels of antioxidant and antityrosinase activities
than ungerminated brown rice. The results showed 24-48 h germination regimes were most
effective in maximizing the antioxidant and antityrosinase activities in germinated brown rice.
Under such conditions, the maximum quantities of total phenolics, total flavonoids and
antityrosinase were detected in Riceberry (25.06 mg GAE/g DW), KDML 105 R-PSL-2 (95.67
mg QE/g DW) and Riceberry (31.33%), respectively. Again, the highest DPPH value of
81.52% was detected in Riceberry and the highest ABTS value of 67.92% in KDML 105 RPSL-
2. Additionally, a strong correlation between antioxidant, antityrosinase and germination
time was detected. The information obtained from this study should provide a foundation for
future research aiming at the development of functional foods and/or cosmetics.
