Could choline chloride-citric acid monohydrate molar ratio in deep eutectic solvent affect structural, functional and antioxidant properties of pectin?

The deep eutectic solvents (DESs), which were made from different molar ratios (3:1, 2:1, 1:1, 1:2, 1:3) of choline chloride and citric acid monohydrate, were used as media for the pectic polysaccharide extraction from Averrhoa bilmbi (ABP). The physico-chemical, structural, functional and antioxidant properties of ABP were subsequently determined. The ABP was found to be xylogalacturonan. Moreover, results showed that different structures (i.e. linearity of pectin and branch size) of ABP were obtained, hence, affecting the solubility and functional properties due to the surface availability and steric effect. In addition, when increasing the molar ratio of citric acid monohydrate in DES, lower pH and higher TPC values were observed. These values were correlated with antioxidant activities (i.e. free radical scavenging activity and ferric reducing antioxidant power) of ABP. In conclusion, the molar ratio of the DES components plays an important role in extracting ABP with the aforementioned properties. •High methoxyl acidic xylogalacturonan was produced.•Different molar ratios in DES extracted pectin with different structural properties•ABP1:2 has the most linear structure and ABP3:1 has the largest branch size.•The functional properties were influenced by their linearity and branch size.•The antioxidant activities were affected by the pectin acidity and phenolic content.