2.2.3 Antioxidant capacity assay
Antioxidant capacity assay (DPPH, FRAP, ABTS and ORAC) was performed
according to Shi et al. (Shi et al., 2017) with a few modifications.
Polar extract was acquired from 2.0 g of oil. The oil was mixed with 7.5
mL methanol in a brown bottle and vigorously stirred for 20 min. The
supernatant was carefully separated as polar extract, and the residue
was extracted four times with 7.5mL of methanol each. All polar extracts
were transferred into a brown vial and stored at -20 °C in darkness
until analysis. Detailed information associated with the methods used
for DPPH, FRAP, ABTS and ORAC were all presented in the supplementary
material.