Ultrasonic-assisted Deep Eutectic Solvents Extraction of Total Flavonoids from Apple Leaves

Objective:To investigate the optimum extraction process of total flavonoids from apple leaves by ultrasonic-assisted method with deep eutectic solvents (DESs) as extractant. Methods:The effects of the composition of DESs, composition ratio, DESs/water ratio, extractant/raw material ratio (mL/g), ultrasound temperature, ultrasound time on the extraction yield of total flavonoids from apple leaves were investigated by single factor tests. Based on the results of the single tests, response surface methodology was employed to establish mathematic model, analyze experimental data, optimize and verify the extraction process parameters. Results:The results of optimum extraction conditions were as follows:Choline chloride/trifluoroacetic acid with molar ratio of 1:2 containing 30% water, extractant/raw material ratio 23:1 mL/g, extraction temperature 72℃, extraction time 27 min. Under these conditions, the average extraction yield was 7.06%. Conclusion:Ultrasonic-assisted method with DESs as extractants could efficiently extract total flavonoids from waste apple leaves, and this study would provide technical supports and theoretical guidance for taking full advantages of waste apple leaves.