Emulsifying and surface properties of citric acid deamidated wheat gliadin

• d-gliadin exhibits high solubility at pH 7.0 with no hydrolysis.
• d-gliadin can form stable emulsions and heat treatment improves their stability.
• Heat treatment induced red shift of λmax indicating molecule rearrangement.
• d-gliadin can significantly lower surface tension at the oil–water interface.

The properties of citric acid deamidated wheat gliadin (d-gliadin) and d-gliadin emulsions at concentrations of 2% and 0.5% at pH 7 and 3 were investigated. d-gliadin exhibited high solubility at neutral pH and had a different molecular weight distribution compared with control gliadin. Stability of d-gliadin emulsion increased after heat treatment. Heat treatment led to a red shift of the fluorescence emission maxima of emulsions, indicating the rearrangement of d-gliadin molecules and increase of the protein structure flexibility at the oil–water interface. The emulsion was sensitive to NaCl up to 150 mM due to electrostatic screening effects. d-gliadin concentration influenced the droplet size and the saturation surface load of emulsion. d-gliadin slowly adsorbed on the oil–water interface during the adsorption process. Higher d-gliadin concentration exhibited higher surface pressure. Surface adsorption properties confirmed that d-gliadin was a good emulsifier in oil–water emulsions.