Supercritical carbon dioxide extraction of seed oil from Opuntia dillenii Haw. and its antioxidant activity

Supercritical carbon dioxide extraction of seed oil from Opuntia dillenii Haw. and its antioxidant activity were investigated in this study. The effects of main operating parameters including extraction pressure, temperature, time and CO₂ flow rate on the extraction yield of seed oil were studied. The maximum extraction yield of 6.65% was achieved at a pressure of 46.96 MPa, a temperature of 46.51 °C, a time of 2.79 h and a CO₂ flow rate of 10 kg/h. The chemical composition of the seed oil was analysed by GC–MS. The main fatty acids were linolenic acid (66.56%), palmitic acid (19.78%), stearic acid (9.01%) and linoleic acid (2.65%). The antioxidant activity of seed oil was assessed by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and β-carotene bleaching test. Both methods demonstrated notable antioxidant activity of seed oil, which is nearly comparable to the references ascorbic acid and butylated hydroxytoluene (BHT). The antioxidant activity of the seed oil was also found to be concentration-dependent.