Study of ω-6 linoleic and ω-3 α-linolenic acids of hemp (Cannabis sativa) seed oil extracted by supercritical CO2 extraction: CCD optimization

In the present study, supercritical CO2 extraction of ω-6 linoleic and ω-3 α-linolenic fatty acids from hemp seed oil is successfully optimized through central composite design (CCD) considering five parameters (temperature, pressure, CO2 flow rate, particle size and co-solvent (ethanol) flow rate (mass % of CO2 flow rate)). Two statistical quadratic models are developed, exhibiting a good prediction of ω-6 linoleic and ω-3 α-linolenic acids concentrations with negligible error. All model parameters are found significant for P < 0.05. Interaction and quadratic terms of temperature are observed to be significant in comparison to linear term, which is found insignificant for P > 0.1. Statistical analysis suggests optimized parameters as temperature, 76 °C; pressure, 300 bar; CO2 flow rate, 13 g min−1; particle size, 0.43 mm and co-solvent flow rate as 8% of CO2 flow rate; which are experimentally verified. Moreover, effects of input parameters on the optimum ratio of ω-6 linoleic and ω-3 α-linolenic acids are investigated and found to be in the range from 2.11 to 3.17. UV spectroscopy estimates chlorophyll a, b and carotene content in hemp oil as (84.0 to 293.9) μg g−1, (46.4 to 216.4) μg g−1 and (4.3 to 66.6) μg g−1, respectively.