4. Conclusions
In the present work, the strong effects of the SC-CO2 fluid extraction parameters on the extraction of lycopene from tomato skin and on the antioxidant activity of the resulting extracts have been demonstrated. Response surface methodology determined that temperature, followed by pressure, was the most significantly effective variable for the SC-CO2 fluid extraction. Lycopene yield continued increasing within the range of temperature (40–100 C) and pressure (20–40 MPa) tested. The increase in flow rate did not result in a significant increase in lycopene yield. Only when the temperature of the supercritical extraction was increased above 70 C did it show great influence on the antioxidant activity and composition of the lycopene isomers. Similar to thermal processing, the lycopene stability and antioxidant level of each unit of lycopene-rich extract decreased with increasing the SC-CO2 fluid extraction temperature above 70 C. No significant influences of pressure and flow rate on the stability and antioxidant activities of SC-CO2 fluid extraction products were observed.