The results on free radical quenching capability of rice
bran oil antioxidants obtained by conventional solvent
and microwave-assisted extractions are presented in
Fig. 7. When isopropanol was used as a solvent, the free
radical quenching capability increased significantly by
increasing the temperature of microwave-assisted extraction,
from 33.61 to 59.85 lmol Trolox Equivalent per gram
of fresh rice bran for 40 and 120 C, respectively. The free
radical quenching capability did not change significantly
for the oil extracted with hexane by microwave-assisted
extraction, even though higher amounts of vitamin E were
extracted (Table 1).