Green Extraction Technique: Subcritical Water Extraction

Abstract

An environmental kindly technique, subcritical water extraction (SWE) are based on using water as extraction solvent at temperatures between 100 °C and 374 °C. Increasing the temperature at moderate pressure also reduces the surface tension and viscosity of water causes the polarity of subcritical water is comparable to organic solvents. Therefore, the subcritical water could be improved the competency for the extraction. The aim of this work was to study the flavonoid content of Emilia sonchifolia (L.) using different extraction procedures (SWE and the traditional extraction or ethanolic extraction). The results revealed that quercetin, a plant-derived flavonoid, was a major component in both extraction procedures. The use of SWE provided higher quercetin content and antioxidant activity. Quercetin content by SWE and traditional extraction were 45.92 mg/ml and 39.94 mg/ml, respectively. The EC50 (Effective Concentration, 50%) of SWE and traditional extraction were 496 and 555.67 mg/ml, respectively. Additionally, this work demonstrated that the traditional time-consuming techniques for 12 hours of the extraction of flavonoids could be substituted for the SWE technique within 1 hour. Consequently, the capability of SWE technique was elaborately evaluated and revealed on this work.  Keywords: Subcritical water; Emilia sonchifolia (L.)