Supercritical CO₂ extraction and antioxidant activity of lycopene and β-carotene-enriched oleoresin from tomato ( Lycopersicum esculentum L.) peels by-product of a Tunisian industry

Lycopene and β-carotene were extracted as oleoresin from a Tunisian industrial tomato peels by-product using supercritical CO₂. Experiments were conducted at temperatures of 50–80 °C, pressures of 300–500 bar and flow rates of 3–6 g CO₂/min for 105 min extraction time. The relative extraction yields varied from 32.02% to 60.85% for lycopene and from 28.38% to 58.8% for β-carotene and only the extraction temperature had a statistically significant effect on the process. The supercritical fluid extraction of lycopene from tomato peels by-product was compared to conventional maceration extraction using hexane, ethyl acetate and ethanol. Besides, the influence of the supercritical CO₂ extraction conditions on the extract antioxidant capacity was evaluated using the quenching activity of the free chromogenic radical, 2,2-diphenyl-1-picrylhydrazyl (DPPH). Important correlation coefficients and models were determined to predict the oleoresin, lycopene and β-carotene extraction yields and the relevant DPPH quenching activity as function of the SFE operation parameters. Interestingly, the supercritical CO₂ extracted oleoresin exhibited competitive antiradical activity with the synthetic antioxidant, butylated hydroxytoluene (BHT). Results showed that the Tunisian industrial tomato peels by-product is a potential source of high antioxidative, solvent free and lycopene and β-carotene-enriched oleoresin with promising applications in food and pharmaceutical industries