Antioxidant effects of hemp (Cannabis sativa L.) inflorescence extract in stripped linseed oil

The ability of hemp (Cannabis sativa L.) inflorescence extract to counteract lipid oxidation was studied in stripped linseed oil. The ethanolic extract was characterized in terms of terpenes (6.00 mg/mL), cannabidiol (4.99% w/w), phenolic compounds (1.80 mg gallic acid equivalents (GAE)/mL), antiradical, and metal ion-chelating activities (50% effective concentration (EC50) of 2.47 mg/mL and 0.39 mg/mL, respectively). The stripped linseed oil, used as control (CO), was mixed with hemp extract (HO) or α-tocopherol (EO) at a ratio of 0.6% (w/w) and stored for 7 days in darkness at 40◦ C. Hemp extract reduced the oxidation and lipolysis processes. At the end of the storage, HO showed a significantly higher level of α-linolenic acid (ALA; 26.64 g/100 g), lower peroxide value (PV) (21.19 meq O2 /kg oil), and lower hexanal content (7.67 mmol/kg oil) than those found in the control. In contrast, EO showed a marked lipolysis (the free fatty acids increased by 42.57%) and a noticeable oxidation, since the ALA content decreased by 2.10% and a PV of 50 meq O2 /kg oil was observed. This study demonstrates that hemp inflorescences can be used as a source of natural antioxidants in vegetable oils and lipid products to retard their oxidation, especially those characterized by a high degree of unsaturation.