Extraction of Curcumin and Essential Oil from Curcuma longa L. by Subcritical Water via Response Surface Methodology

In this study, subcritical water extraction (SWE) was applied to extract the essential oil (especially curcumin) from Curcuma longa L. (turmeric) rhizome. Response surface methodology was used to evaluate the extraction conditions. Experiments were carried out using a three-factor Box-Behnken design under following conditions: temperature (90, 120 and 150C), water flow rate (1, 2.5 and 4 mL/min) and mean particle size (0.5, 1 and 1.5 mm). This is the first time that effects of mentioned variables were considered on SWE of curcumin. The optimum conditions were temperature of 150C, water flow rate of 1 mL/min and mean particle size of 0.5 mm. The maximum curcumin extraction yield was 90.1947 +/- 0.26%, which was in a good agreement with the predicted value of 92.0097%. The extracts were analyzed by gas chromatography and gas chromatography-mass spectrometry. Also, results of SWE were compared with conventional methods.