Extraction of Antioxidants from Strawberry Leaves with Supercritical Carbon Dioxide and Water Mixtures

Strawberry leaves contain useful components such as antioxidants and phenolics and are generally discarded after receptacles have been harvested. The recovery of useful components by an environmentally friendly and harmless method will promote the effective utilization of whole strawberry. In this study, extraction of strawberry leaves with supercritical CO2(sc-CO2) + water solvent, which consists of CO2 having a lower polarity and water having a high polarity, was examined, and antioxidant capacity (AOC) and total phenolic content (TPC) of extract were evaluated at 308 333K, 10-30MPa and 0.1-0.3 of H2O/CO2 molar ratio. The AOC and TPC obtained in sc-CO2+ water were larger than those in sc-CO2, which means that water improved the extraction. AOC and TPC at 308K and 20 MPa had maximal values against H2O/CO2 molar ratio. AOC and TPC at 20 MPa against temperature and those at 308K against pressure had minimum value. This trend was probably due to the effect of solvent density and solubility. The response surface modeling method was applied to optimization for temperature and pressure at H2O/CO2- 0.1 and 120min of extraction time, and AOC and TPC were maximum at 308K and 17.0 MPa, and 333 K and 22.4 MPa, respectively.