Effect of water bath temperature on flavonoid contents: The treated jujube powder 2 g was placed in a flat-bottomed flask, added 50 mL of 50% ethanol solution at 50 °C, 60 °C, 70 °C, 80 °C water bath heated for 30 min respectively, filtrated and the volume was 100 mL. The absorbance value was measured, and the flavonoid contents was calculated.