Physico-chemical properties, adsorption capacity and anti-oxidization of lignin and cellulose separated from mung bean skin by deep eutectic solvent treatment.

The health function of mung bean skin is closely related to its physico-chemical and physiological properties. However, current research ignores the interaction of the physico-chemical and physiological properties of mung bean skin lignin, mung bean skin cellulose and homologous mung bean skin. The extraction of lignin and cellulose from mung bean skin was conducted using a deep eutectic solvent based on choline chloride-lactic acid. A structural analysis of mung bean skin lignin was conducted using ultraviolet (UV), Fourier-transform infrared (FTIR), and proton-nuclear magnetic resonance (1H-NMR), which revealed its classification as SGH-type lignin. The predominant bonds between mung bean skin lignin monomers were β-O-4 linkages. Functionally, compared with mung bean skin cellulose and mung bean skin, mung bean skin lignin showed significantly (P < 0.05) higher oil-holding capacity. In contrast, mung bean skin cellulose exhibited significantly (P < 0.05) higher water-retention capacity in comparison to both mung bean skin lignin and mung bean skin. The in vitro absorption capacity of cholesterol and sodium cholate for mung bean skin lignin was found to be considerably higher than that of mung bean skin cellulose and mung bean skin. Furthermore, in terms of in vitro antioxidant activity, mung bean skin lignin exhibited superior ABTS+· (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic)) and DPPH· (1,1-diphenyl-2-picrylhydrazyl) radical scavenging ability compared to mung bean skin cellulose and mung bean skin. Mung bean skin lignin has potential application value in functional foods for regulating blood lipid and oxidative stress.