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

Abstract

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.