Drying treatment impact on oil yield extracted from black soldier fly larvae using supercritical carbon dioxide and its biological activities
Black soldier fly (Hermetia illucens) larvae are considered economically viable as an alternative source of oil and bioactive compounds. The drying and extraction methods are critical steps in the extraction of oil and have an impact on the characteristics and composition of the extracted oil. Supercritical CO2 extraction of oil from black soldier fly larvae allows for the extraction of important bioactive compounds and oils while causing the least amount of change. The effect of different pre-treatment tray-drying and freeze-drying methods on the quantity and biological activities of oil extracted from black soldier fly larvae using supercritical CO2 was investigated in this study. Oil extraction from tray-dried and freeze-dried black soldier fly larvae samples could be done at low temperatures for a shorter extraction time, resulting in higher yields while avoiding the negative effects of high temperatures on lipids and other valuable components. The oil extracted from tray-dried and freeze-dried black soldier fly larvae contained major fatty acid compositions such as lauric acid, linoleic acid, oleic acid and palmitic acid, as well as total phenolic compounds (0.067-0.113 mg gallic acid/g oil), antioxidant capacity 2,2-diphenyl-1-picrylhdrazyl (DPPH) (0.36-0.56 mmol Trolox equivalent antioxidant capacity (TEAC)/10 g oil), and antioxidant capacity 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) (0.23-0.55 mmol TEAC/10 g oil, and ferric reducing antioxidant power antioxidant capacity (0.33-0.64 mmol TEAC/10 g oil). The oil extracted from tray-dried and freeze-dried larvae samples had a shelf life of approximately 2.42-3.63 months and 2.51-3.40 months, respectively, at storage temperatures ranging from 25 to 55 °C. The oil extracted from tray-dried and freeze-dried larvae samples extracted using supercritical CO2 had high acid values which could inhibit keratinocyte growth by 76.70 and 75.04%, respectively, at 100 mg/ml concentrations. Furthermore, the tray-drying and freeze-drying methods had no effect on the physicochemical properties of the supercritical CO2-extracted oil from dried black soldier fly larvae samples.