The "natural" food colorants, carotenoids, are of great importance to human health. In an effort to enhance the efficiency of SC-CO2 extraction of carotenoids from carrots, canola oil was investigated as a continuous co-solvent. The carotenoid content of the starting material was determined by traditional solvent extraction (TSE). Carrot samples with different particle size and moisture content were extracted with SC-CO2 at different temperature, pressure, canola oil concentration and CO2 flow rate for 4 It. Carotenoids were identified and quantified by HPLC analysis. alpha-Carotene, beta-carotene, and lutein were the main carotenoids in the extracts. When canola oil was added as a co-solvent, the alpha- and beta-carotene yields were improved more than twice and lutein yield was more than four times higher compared to those obtained with SC-CO2 extraction alone. Both increasing temperature and increasing pressure had significant positive effects on the carotene yields except for that of lutein. Larger particle size had a negative effect on carotenoid yields. The a- and P-carotene yields decreased with moisture while the lutein yield increased. Higher carotenoid yields were achieved after 4 h of extraction at higher flow rate, while more carotenoids were solubilized in SC-CO2 at lower flow rate. The highest carotenoid yields were obtained at 70 degrees C, 55.1 MPa, 5% canola oil concentration (w/w of CO2), 0-25-0.5 turn particle size, 0.8% moisture content of feed material, and 2 L/min CO2 flow rate. Employing canola oil as a continuous co-solvent in SC-CO, extraction is a novel and efficient technique for the recovery of carotenoids from natural materials. (c) 2006 Elsevier B.V. All rights reserved.