Hydrophobic deep eutectic solvents for carotenoid extraction from tomato pomace: Solvent screening and effect of extraction conditions

This study evaluated the extraction of carotenoids from tomato pomace using hydrophobic eutectic solvents (HDES) as a green alternative to conventional solvents. An initial screening of forty-nine HDES composed of fatty acids and alcohols was performed using the COSMO-RS model. The most promising HDES, composed of octanoic acid and decanoic acid (1.8,1), was selected for investigation of process parameters. Then, a Central Composite Rotational Design was employed to investigate the effects of temperature (21-49 °C) and biomass-to-solvent ratio (1,3-1,17) on the extraction efficiency. Temperature was the most significant factor affecting carotenoid recovery, with higher extraction yields (>140 μg/g) achieved at higher temperatures. Compared to vegetable oils, HDES exhibited superior performance, attributed to their composition of free fatty acids, lower viscosity and lipophilic affinity. Lycopene, β-carotene, and lutein were identified in the extracts, with Z-lycopene reaching 27% of total lycopene, suggesting partial isomerization during extraction process.