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

Biorefinery cascade processing for creating added value on tomato industrial by-products from Tunisia

Background: In today’s consumer perception of industrial processes and food production, aspects like food quality, human health, environmental safety, and energy security have become the keywords. Therefore, much effort has been extended toward adding value to biowastes of agri-food industries through biorefinery processing approaches. This study focused, for the first time, on the valorization of tomato by-products of a Tunisian industry for the recovery of value-added compounds using biorefinery cascade processing. Results: The process integrated supercritical CO2 extraction of carotenoids within the oil fractions from tomato seeds (TS) and tomato peels (TP), followed by a batch isolation of protein from the residues. The remaining lignocellulosic matter from both fractions was then submitted to a liquid hot water (LHW) hydrolysis. Supercritical CO2 experiments extracted 5.79% oleoresin, 410.53 mg lycopene/kg, and 31.38 mg β-carotene/kg from TP and 26.29% oil, 27.84 mg lycopene/kg, and 5.25 mg β-carotene/kg from TS, on dry weights. Protein extraction yields, nearing 30% of the initial protein contents equal to 13.28% in TP and 39.26% in TS, revealed that TP and TS are a rich source of essential amino acids. LHW treatment run at 120–200 °C, 50 bar for 30 min showed that a temperature of 160 °C was the most convenient for cellulose and hemicellulose hydrolysis from TP and TS, while keeping the degradation products low. Conclusions: Results indicated that tomato by-products are not only a green source of lycopene-rich oleoresin and tomato seed oil (TSO) and of protein with good nutritional quality but also a source of lignocellulosic matter with potential for bioethanol production. This study would provide an important reference for the concept and the feasibility of the cascade fractionation of valuable compounds from tomato industrial by-products