Response surface optimization of supercritical fluid extraction of kaempferol glycosides from tea seed cake

The aim of this study was to develop a fast and efficient procedure for the purification of two kaempferol glycosides (kaempferol-3-O-[2-O-β-d-galactopyranosyl-6-O-α-l-rhamnopyranosyl]-β-d-glucopyranoside and kaempferol-3-O-[2-O-β-d-xylopyranosyl-6-O-α-l-rhamnopyranosyl]-β-d-glucopyranoside) from tea seed cake using supercritical fluid extraction (SFE). The procedure was optimized by response surface methodology (RSM) using a quadratic polynomial model. Extraction time, pressure, temperature and ethanol content of modifier were selected as the independent variables. From response surface plots, interactive effects of the four independent variables could be seen on the yield of the two kaempferol glycosides. Conditions to obtain the highest total yield were determined to be an extraction time of 150 min, pressure of 20 MPa, temperature of 80 °C, and 60% aqueous ethanol solution. Using the optimal conditions, the experimental yield was 11.4 ± 0.4 mg/g, which was similar to the value predicted by the model. Moreover, compared with the conventional extraction method, SFE consumed less organic solvent and shorter time.