Rapid and selective concentration of lycopene Z-isomers from tomato pulp by supercritical CO₂ with co-solvents

This study aimed to efficiently separate and concentrate lycopene Z-isomers from tomato pulp using supercritical CO₂ (SC-CO2). The separation relies on the different solubility of (all-E)-lycopene and the Zisomers. Total lycopene recovery using SC-CO₂ at 50 °C and 30 MPa for 1 h was extremely low (1.2%). Thus, before the separation test, an optimal co-solvent was selected from water, organic chemicals, and edible vegetable oils; hazelnut oil, which had the highest lycopene recovery (21.6%), was adopted. When using hazelnut oil as a co-solvent, the extraction of lycopene Z-isomers was completed in a short time compared to (all-E)-lycopene. Furthermore, when the extraction was conducted at higher pressure (50 MPa) and temperature (80 °C), the Z-isomer content decreased due to the improvement of (all-E)-lycopene solubility. Thus, to selectively and efficiently extract lycopene Z-isomers, addition of a co-solvent, and a relatively short contact time, low pressure, and low temperature extraction were important.