Abstract: Objective: Orthogonal array design was used to optimize the microwave-assisted extraction of total flavonoids from Chinese date seeds. Methods: Total flavonoids were spectrometrically determined using rutin as a reference compound. The effects of microwave power, extraction time, temperature, solid-to-solvent ratio and ethanol concentration on the extraction yield of total flavonoids were investigated by one-factor-at-a-time experiments. Subsequently, these extraction parameters were optimized by orthogonal array design. Results: Five extraction parameters were ranked in descending order of their effect on the extraction of total flavonoids as follows: solid-to-solvent ratio＞extraction temperature＞extraction time＞ethanol concentration＞microwave power. Their optimal levels were 1:60 (g/mL), 60 ℃, 20 min, 50% and 500 W, respectively. Under these conditions, the extraction yield of crude total flavonoids was 10.14%, and the total flavonoid content of the extract obtained was 7.00%. Conclusion: The extraction efficiency of total flavonoids from Chinese date seeds is remarkably increased by microwave extraction and orthogonal array optimization.

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