Optimization of ethanol-assisted aqueous oil extraction from Cicadatra querula

Edible insects are being considered as high-quality protein and lipid content sources in recent decades. Cicadatra querula is a seasonal edible insect with a large potential. Moreover, seeking alternative green solvents is an integral approach to limiting toxic and hazardous solvents as hexane in industrial sectors. In this study, the ethanol-assisted aqueous extraction (EAAE) method and the hexane extraction (HE) method were applied to extract the insect oil. Furthermore, oil recovery (%), chemical properties, and fatty acid profiles of both extracted oils were evaluated. According to Box–Behnken design for EAAE method, three levels of variables including pH (5, 6, and 7), ethanol/water ratio (10, 30, and 50% (v/v)), and liquid/solid ratio (5, 10, and 15 mL/g) were examined. The mentioned ranges of variables were optimized in order to achieve the highest oil extraction efficiency and the maximum recovery was obtained at 69.42% for pH of 5.95, ethanol/water ratio of 33.59% (v/v), and liquid/solid ratio of 12.30 mL/g, in comparison with HE method. The acid value for EAAE was considerably lower at 1.49, as compared to for HE at 2.10. The primary fatty acids in the HE method were oleic, palmitic, and linoleic at 66.5, 19.2, and 7.8%, respectively, compared to these numbers for EAAE at 66.3, 17.7, and 9.5%, respectively.