Exploring alternative solvents to n-hexane for green extraction of lipid from camellia oil cakes

<i>Camellia oleifera</i> Abel. is an important woody oilseed tree to help increase the self-sufficiency rate. In this study, lipid extraction focuses more on the solvent extraction of Camellia seed oil (CO) cakes rather than conventional cold pressing, where the performance of candidate alternative green solvents selected from hurdle technology was first evaluated. Compared to n-hexane (89.50 ± 0.00 %) and subcritical n-butane (83.75 ± 0.43 %), 2-methyloxolane (2-MeOx) performed the best with the comprehensive consideration of extraction ratio (94.79 ± 0.00 %), lipid composition and environmental impact (0.38 ± 0.07 kg of CO₂ emission). Intriguingly, 2-MeOx exhibited the highest diffusion rate at both 25 °C and 55 °C in the extraction kinetic study, which could also extract the highest total phenolic contents (351.6 ± 0.02 mg GAE/kg dw) corresponding to its best oxidative stability. Besides, Hansen solubility modeling could help better understand the dissolving mechanism. 2-MeOx was demonstrated as the optimal alternative bio-based solvent to n-hexane with comparable extractability and selectivity in the CO extraction.