Citrus bioactive limonoids and flavonoids extraction by supercritical fluids
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The increasing use of organic solvents for extraction of bioactive compounds is a significant environmental concern. In the present report, limonoids and flavonoids were extracted from grapefruit (Citrus paradisi Macf.) seeds by an environmentally-friendly supercritical CO 2 extraction (SC-CO 2) technique. Optimum conditions for extraction of limonoid aglycones, such as pressure, temperature, extraction time, CO 2 flow rate and the feeding modes of CO 2, were determined. The highest yield of limonin was 6.3 mg/g seeds at 48.3 MPa, 50C and 60 min with CO 2 flow rate of approximately 5.0 1/min being fed from the top of the column. The highest extraction yield of limonin glycoside was 0.62 mg/g defatted seeds which was obtained at 48.3 MPa, 50C and 30% ethanol in 40 min with flow rate of SC-CO 2 of 5.0 1/min and fed from the top of the column. Furthermore, the maximum extraction of naringin (0.2 mg/g defatted seeds) was obtained under the conditions of 41.4 MPa, 50C, 20% ethanol, 40 min with CO 2 flow rate of approx. 5.0 1/min. The results demonstrated practical commercial application of SC-CO 2 extraction of limonoids and flavonoids from grapefruit seeds. 2006 American Chemical Society.