Comparative evaluation of hemp seed oil yield and physicochemical properties using supercritical CO2, accelerated hexane, and screw press extraction techniques

This study evaluated screw press, accelerated hexane, and supercritical CO₂ extraction techniques to identify the optimal method for maximizing cannabidiol (CBD) yield from hemp seed oil. Supercritical CO₂ extraction at 40 °C and 200 bar yielded 20.81 % oil with the highest average CBD concentration of 603.57 μg/mL. At this condition, the oil exhibited an acid value of 30.73 mg KOH/g oil, a peroxide value of 17.10 meq O₂/kg oil, an iodine value of 103.21 g I₂/100 g oil, and a saponification value of 185.34 mg KOH/g oil. The total phenolic content, measured as 0.08 mg gallic acid equivalents/g oil, corresponded with antioxidant activities of 1.22 and 1.35 μmol Trolox equivalents/g oil in the ABTS and DPPH assays, respectively. The extracted oil also showed high levels of chlorophyll and carotenoids and an optimal fatty acid composition with an ω-6 to ω-3 ratio of 3.98. These findings demonstrate that supercritical CO₂ extraction at this condition is an effective method for obtaining CBD-rich hemp seed oil with desirable chemical and antioxidant properties.