Effects of five extraction methods on total content, composition, and stability of flavonoids in jujube

Abstract

The present study investigated the effects of different extraction methods including water-water bath (W-WB), ethanol-water bath (E-WB), deep eutectic solvent (DES) combined with ultrasound-assisted extraction (DES-UAE), microwave-assisted extraction (DES-MAE), and enzyme-assisted extraction (DES-EAE) on flavonoids (total flavonoid content, flavonoid composition, and stability) in jujube. The highest total flavonoid content of 8.03mg/g was obtained by the DES-MAE extraction. Fifteen types of flavonoids were identified from jujube. The amount of rutin produced by the E-WB and DES-UAE methods was 66.88±1.58μg/g and 45.23±3.22μg/g, respectively. The retention of flavonoids in DES-UAE extracts were 98.15±0.51%, 64.25±2.21% after 2h of high temperature treatment at 90°C and 21days of dark storage, respectively. The flavonoids extracted by different methods were suitable for dark storage under different light contrasts, where the retention of flavonoids extracted by DES-UAE method was 86.44±2.45%. In conclusion, DES-UAE would be an efficient method for flavonoid extraction from jujube.