2.3. Soxhlet extraction (SE) process
Rice bran was placed into a cellulose paper cone and extracted for 6 h in a Soxhlet extractor at 90 ℃ with n-hexane according to the Soxhlet standard extraction method (AOAC, 1997). The oil was then recovered by evaporating off the solvent at 50 ℃ under reduced pressure using a rotary evaporator Model RE-2000A (Yarong Biochemical Instrument Factory, Shanghai, China) and residual solvent was removed by flushing with 99.99% nitrogen. This technique produced 18.45 ± 0.25 g of oil per 100 g of rice bran, which was set as 100% oil recovery for comparison. The recovered oil was stored at 4 ℃ until use.