A comprehensive study on the relationship between structure and antioxidant activity of natural deep eutectic solvent extracted polysaccharides from Chinese yam peel using asymmetrical flow field-flow fractionation

In this study, an ultrasound-assisted natural deep eutectic solvents (NADES) combined with enzymatic deproteinization was developed for extracting Chinese Yam peel polysaccharide (CYPP) from two varieties. The result demonstrated that the viscosity of NADES was the primary factor affecting the extraction rate of CYPP. Under optimized extraction conditions, the CYPP extraction rate obtained by NADES was 2.42-fold higher than that obtained by the water extraction method. Moreover, the relationship between the structure and antioxidant activity of CYPP was investigated using asymmetrical flow field-flow fractionation (AF4), Fourier transform infrared spectroscopy, and Congo red assay. The results suggested that NADES extraction method did not alter the functional groups and triple-helix structure of CYPP. Notably, the AF4 results suggested that NADES extracted CYPP had a relatively compact structure, which might play a crucial role in the antioxidant activities of CYPP than either its triple-helix structure or uronic acid content.