Ultrasound assisted hydrotropic extraction of polyphenols from green tea leaves in aqueous media

A green approach of combining hydrotrope assisted extraction with ultrasound was adopted to extract the polyphenols from tea leaves. This process significantly reduced extraction time and solvent quantity, while enhancing the quality of the final product. Sodium cumenesulfonate (NaCuS), sodium p-toluenesulfonate (NaPTS) and sodium xylenesulfonate (NaXS) were chosen for solubilizing tea polyphenols. Among the hydrotropes used, NaCuS proved to be efficient particularly in solubilizing tea polyphenols. The extraction process was thoroughly studied by varying factors such as the solid to solvent ratio (S/N), ultrasonic duration and temperature. Comprehensive solubility studies of polyphenols were conducted across different solvents, pH levels, temperatures, treatment durations and solid loadings. To optimize the experimental parameters, a central composite design (CCD) of response surface methodology (RSM) was employed. The results demonstrated that a polyphenol extraction efficiency of 68.429% was achieved at a solid to solvent ratio of 0.05, ultrasonic time of 3.2 h and temperature of 49.9 °C. This research firmly established the effectiveness of ultrasound assisted extraction for obtaining polyphenols from green tea in a highly efficient manner.