Combining electrochemically-induced deamidation and polysaccharides treatment improved emulsifying properties and...

The high content of amide groups in natural wheat gliadin (WG) limits its application in the food industry. In this paper, the amide group of WG was transformed into carboxyl group by electrochemical technology to obtain deamidated wheat gliadin (DWG). Then the hydrophilic polysaccharide was combined with DWG to further improve the polarity and oil-water balance of DWG. The effects of different polysaccharides (sodium alginate and xanthan gum (XG)) and different concentrations on the emulsion system and interfacial properties of DWG were explored. The structure-effect relationship between the DWG-polysaccharide composite emulsion and the conformational transformation of interfacial protein was analyzed. Results showed that the properties of WG emulsion were substantially improved after electrochemically-induced deamidation combined with polysaccharide treatment. The particle size, ζ-potential, turbidity and flocculation index of the emulsion decreased, and the physical stability, antioxidant activity and interfacial adsorption capacity increased. Among them, DWG-0.3XG stabilized the emulsion by electrostatic repulsion and steric hindrance, showing the lowest particle size (456.42 nm), the highest percentage of adsorbed proteins (82.34%), interfacial pressure and emulsion stability. Furthermore, electrochemically-induced deamidation combined with polysaccharide treatment induced conformational changes of interfacial proteins, decreased α-helix and β-sheet contents, decreased surface hydrophobicity, enhanced polarity, and unfolded protein structure, uniformly dispersed proteins were more conducive to stabilizing the emulsion. These results will provide a new perspective for the expansion of WG emulsion and give a hand for the characterization and application of WG.