(i) Cold pressing technique and storage at low temperature (4°C) in dark [36]. (ii) Komet screw press at 25–30°C using electrical resistance heating. (1) Pro: better preservation of antioxidant contents (quercetin and myricetin) than solvent extraction [37]. (2) Con: only partial recovery of oil yield [38].
Solvent
(i) Soxhlet method using n-Hexane (less preferable than other methods). (1) Pro: it favors the functional characteristics of the oil such as water holding and absorption capacity, organic molecule absorption, and emulsifying stability. (2) Con: it causes slight loss of antioxidant content [37] and health and environment safety issues of using hexane [38].
Supercritical fluids
(i) Use of carbon dioxide at optimum pressure P = 408 and 80°C (more preferable method). (1) Pros: better purity and higher ALA/LA content of the final products [39, 40]. The oil yield can be increased with pressure enhancement, but high temperature will slightly affect it [40].
