Supercritical CO2 extraction of curcumins and essential oil from the rhizomes of turmeric (Curcuma longa L.)

Turmeric rhizomes were extracted with supercritical CO2 and supercritical CO2 + ethanol. Extraction experiments were carried out at pressures of 25 and 30 MPa and temperatures of 313 and 318 K. The influence of the drying temperature of the raw material on the extraction yield and curcuminoids profile was evaluated. The higher content of curcuminoids in the extracts was obtained by supercritical fluid extraction from rhizomes dried at 343 K using CO2 + ethanol. The identification of curcuminoids in both the extract and the residual solid was performed by both spectrophotometry and HPLC. The composition of the essential oil was determined by gas chromatographic mass spectrometry. A mathematical model was used to describe the overall extraction curves. The mass transfer inside the solid matrix was described by a linear first-order desorption model, whereas the transfer in the fluid phase was described by a convective mass-transfer model. The mathematical model fitted well the experimental data.