Characterization and Benzo[a]pyrene Content Analysis of Seed Oil Extracted by a Novel Subcritical Fluid Extraction.

A novel continuous subcritical -butane extraction technique for seed oil was explored. The fatty acid composition, physicochemical properties, and benzo[a]pyrene content of seed oil extracted using this subcritical technique were analyzed. Orthogonal experiment design (L(3)) was adopted to optimize extraction conditions. At a temperature of 45 °C, a pressure of 0.5 MPa, a time of 50 min and a bulk density of 0.7 kg/L, an extraction yield of 99.12 ± 0.20 % was obtained. The major components of seed oil are oleic acid (73.12 ± 0.40 %), palmitic acid (10.38 ± 0.05 %), and linoleic acid (9.15 ± 0.03 %). Unsaturated fatty acids represent 83.78 ± 0.03 % of the total fatty acids present. Eight physicochemical indexes were assayed, namely, iodine value (83.00 ± 0.21 g I/100 g), saponification value (154.81 ± 2.00 mg KOH/g), freezing-point (-8.00 ± 0.10 °C), unsaponifiable matter (5.00 ± 0.40 g/kg), smoke point (215.00 ± 1.00 °C), acid value (1.24 ± 0.03 mg KOH/g), refrigeration test (transparent, at 0 °C for 5.5 h), and refractive index (1.46 ± 0.06, at 25 °C). Benzo[a]pyrene was not detected in seed oil extracted by continuous subcritical -butane extraction. In comparison, the benzo[a]pyrene levels of crude seed oil extracted by hot press extraction and refined seed oil were measured at 26.55 ± 0.70 and 5.69 ± 0.04 μg/kg respectively.