Thermal and light stabilities and antioxidant activity of carotenoids from tomatoes extracted using an ultrasound-assisted completely solvent-free method

The use of petroleum-derived solvents, particularly volatile organic compounds (VOCs), in the chemical industry has increased the contamination and residual effects of these solvents. Ionic liquids (ILs) can potentially replace VOCs, thereby reducing the risks of environmental contamination and toxicity. In this context, the objectives of this study were as follows: 1 - to obtain an ionic liquid for use in extracting carotenoids from tomatoes with ultrasound assistance; and 2 - to determine the stability and antioxidant activity of tomato carotenoid extracts. Ultrasound can also efficiently extract carotenoid compounds with ionic liquids in comparison with conventional VOC solvents (obtained from an all-trans-lycopene 7.5-8.0 mu g.g(-1) tomato sample by IL and 6.2-7.7 mu g.g(-1) by acetone). Similarly, the activation energies (E-a) in aqueous medium were obtained for the IL carotenoid extract (10.8 kJ.mol(-1)) and acetone carotenoid extract (9.4 kJ.mol(-1)). The antioxidant activities of the tomato carotenoid extract were 7.4 and 12.4 relative to alpha-tocopherol for the ionic liquid extract and acetone extract, respectively. The combination of chromatographic analysis and degradation kinetics provided data for positive assessment similarity of thermal and light stabilities of tomato carotenoids extracted by IL and extracted by acetone. (C) 2016 Elsevier Ltd. All rights reserved.