Extraction conditions affecting supercritical fluid extraction (SFE) of lycopene from watermelon

Lycopene, a carotenoid linked to protection against certain forms of cancer, is found in produce such as papaya, red-fleshed tomatoes, grapefruit and watermelon. The preparation of a supercritical CO2 (SC-CO2) watermelon-lycopene extract could serve as a food grade source of this carotenoid. This study established preliminary conditions for enhancing SGCO(2) extraction of lycopene from watermelon. Freeze-dried watermelon was extracted with SGCO(2) and ethanol as an organic co-solvent. The lycopene concentration was determined by HPLC, with absorbance measured at 503 nm. In an initial set of experiments, the effects of extraction temperature (70-90 degrees C), pressure (20.7-41.4 MPa) and co-solvent ethanol addition (10-15%) were evaluated. A lycopene yield of 38 mu g per gram of wet weight was obtained at 70 degrees C, 20.7 MPa, and 15% by volume ethanol. The extraction of fresh (non-freeze-dried) watermelon yielded 103 +/- 6 mu g lycopene per gram fresh fruit Weight. Of the parameters tested, temperature had the most effect on lycopcne yield. Thus, in another set of experiments, the temperature was varied from 60-75 degrees C at an extraction pressure of 20.7 MPa in the presence of 15% ethanol. Studies showed that freeze-dried watermelon flesh loses lycopene in storage. In accounting for lycopene storage losses, lycopene yields at 60 degrees C extraction temperature were 14% greater than those obtained at 70 degrees C. (C) 2008 Elsevier Ltd. All rights reserved.