Abstract: Objective: The optimal conditions for ultrasonic extraction of total flavonoids from Chinese date seeds were investigated by orthogonal array design. Methods: The content of total flavonoids was determined spectrometrically using rutin as reference substance. The effects of ultrasonic power, extraction time, material/liquid ratio, ethanol concentration on the content of total flavonoids in extracts were investigated by one-factor-at-a-time method, and the extraction conditions were optimized by orthogonal array design. Results: Ethanol concentration and ultrasonic power were the key factors that affect the extraction of total flavonoids. The optimal extraction conditions were obtained as follows: ultrasonic power 450 W, treatment time 30 min, material/liquid ratio 1:50 and ethanol concentration 50%. Under these conditions, the extraction yield of crude total flavonoids from Chinese date seeds was 7.04% and the content of total flavonoids in crude extracts 1.59%. Conclusion: The optimized process remarkably increases the extraction yield of total flavonoids from Chinese date seeds and has a promising prospect for practical applications.

Key words: orthogonal array design, ultrasonic, extraction, Chinese date seeds, total flavonoids