Abstract: The shoot of Geum japonicum Thunb. var. chinense F. Bolle was ultrasonified in ethanol-ammonium salt two-phase aqueous system to accelerate the extraction of total polyphenols. Operating parameters such as solid-to-liquid ratio, volume ratio of initial ethanol to initial water, temperature and extraction time were optimized by one-factor-at-a-time and orthogonal array design methods for maximizing the extraction yield of total polyphenols. Solid-to-liquid ratio of 1:20 (g/mL), volume ratio of initial ethanol to initial water of 0.8, ammonium sulfate concentration of 0.27g/mL, extraction temperature of 60 ℃ and extraction time of 60 min were found optimal. Under the optimal extraction conditions, the extraction yield of total polyphenols was 3.04%. This method can provide a novel approach for the extraction of total polyphenols with highly efficient, time-saving and energy-saving benefits and no impact on the biological activity of extracts.

Key words: two-phase aqueous system, ultrasonic, Geum japonicum Thunb. var. chinense F. Bolle, total polyphenols