Deep-eutectic solvent extraction of ginsenosides and ginseng polysaccharides from ginseng residue and utilization of post-extraction residue

In this study, ginsenosides and polysaccharides were extracted from ginseng residue (GR) using a green method combining deep eutectic solvent (DES) and ultrasound. The results showed that the optimal extraction conditions of ginsenosides optimized by orthogonal test were choline chloride/propionic acid ratio of 1:3, moisture content of 30 %, solid-liquid ratio of 1:25, and ultrasound time of 30 min, which resulted in the yield of ginsenosides of 36.76 ± 1.46 mg/g, and improved the efficiency by 218.27 % compared with that of the traditional 70 % ethanol extraction method. The ginseng polysaccharides obtained by further purification of the extract showed different in vitro antioxidant activities, with scavenging rates of 91.2 %, 98.3 %, and 96.4 % for hydroxyl radicals, DPPH, and superoxide radicals, respectively, and Fe(Ⅱ) chelating activity at 93.5 %. The extracted GR showed good adsorption properties for glucose, sodium nitrite, cholesterol, and sodium cholate by in vitro adsorption tests with adsorption rates of 60 %, 93.3 %, 87.05 %, and 72.95 %, respectively. In conclusion, the use of DES as an extraction solvent has certain application prospects for GR reuse.