Supercritical fluid extraction of limonoids and naringin from grapefruit (Citrus paradisi Macf.) seeds

Limonoids and naringin were extracted from grapefruit (Citrus paradisi Macf.) seeds by a supercritical carbon dioxide (SC-CO2) extraction technique. Prominent limonoids such as limonin and limonin-17-beta-D-glucopyranoside (LG) and flavonoid naringin were quantified for process optimization. Extraction was completed in two stages. In stage one less polar limonin was extracted using SC-CO2 while in stage two extraction of high polar LG and naringin were completed using SC-CO2 modified by ethanol as co-solvent. Extraction parameters were studied using Box-Behnken experiment design. Response surface analysis (RSA) of the data was completed to determine effects of variables on extraction efficiency. Highest yield of limonin (6.3 mg/g seeds) was achieved at 48.3 MPa pressure, 50 degrees C temperature and 60 min of extraction time where as highest yield of LG (0.62 mg/g seeds) was achieved at 41.4 MPa pressure, 60 degrees C temperature and 30% ethanol concentration in 40 min. Highest yield of naringin (0.2 mg/g seeds) was achieved at 41.4 NlPa pressure, 50 degrees C temperature and 20% ethanol concentration in 40 min. In all the experiments, mobile phase flow rate was kept constant at 5.0 L/min. The results demonstrated environmentally friendly, practical application of supercritical CO2 extraction of limonoids and flavonoids from grapefruit seeds. (c) 2007 Elsevier Ltd. All rights reserved.