Removal and recovery of deep eutectic solvent with membrane-based methodology: A promising strategy to enhance extraction and purification of Dendrobium officinale flavonoids

Finding efficient, environmental friendly extraction and purification methods of natural active substances has always been a research hotspot in the field of food. In this study, the yield (36.76 +/- 2.17 mg/g) of Dendrobium officinale flavonoids (DOFs) was significantly increased by ultrasonic-assisted deep eutectic solvent (DES) method. DES was removed and recovered from the Dendrobium officinale extracts by bipolar membrane elec-trodialysis (BME). At 70 V, the removal ratios of choline chloride (ChCl) and lactic acid (Lac) could reach 92 % and 90 %, and DOFs were further enriched. Then, Dendrobium officinale polysaccharides (DOPs) was effectively separated from DOFs component using ultrafiltration (UF). After BME-UF treatment, the purification efficiency of DOFs by macroporous resin (MR) was increased by 2.1 times. UPLC-Triple-TOF/MS results further confirmed that, the content of DOFs was increased by 59 times after purification. This study suggested that BME-UF was a valid method for purification of flavonoids, which also promoted green extraction.