Disturbing egg yolk protein structure via pH-shifting treatment for interface reorganization: Improving solubility to enhance oil-water interface adsorption and emulsification properties

This study explored the impact of varying alkalinity levels in pH-shifting treatments on egg yolk protein (EYP) emulsification and investigated the underlying oil-water interface adsorption mechanism. Increasing alkaline pH-shifting treatment exposed more hydrophobic groups within EYP, altering its tertiary structure. Moreover, pH-shifting treatment reduced solution particle size (P < 0.05), possibly by disintegrating insoluble egg yolk granules (EYG) into smaller subunits. Under pH 12.0-shifting conditions, egg yolk (EY) solution reached minimum turbidity and maximum solubility (81.62 %). During initial adsorption, pH 9.0-shifting solution exhibited maximum diffusion rate (0.049 mN/m/s), correlated with minimum solution particle size (88.36 nm). Subsequently, alkaline pH-shifting induced protein rearrangement at the oil-water interface, leading to maximum interfacial pressure (21.01 mN/m) and viscoelastic modulus (44.55 mN/m) under pH 12.0-shifting conditions. This increased emulsion stability by 23.82 % with the lowest creaming index (21.82 %). These findings were crucial for enhancing EYP utilization and promoting EY as a food emulsifier.