The impact of structural properties on the absorption of hen egg-white ovotransferrin with or without Fe3+ at the air/oil-water interface

This study investigated the impact of structural changes (particle size, potential, hydrophobicity, circular dichroism spectra) in ovotransferrin with and without Fe³⁺ (holo-OVT and apo-OVT) on their interfacial behaviors. Holo-OVT exhibited greater diffusion, penetration, and rearrangement rates at the oil-water interface, whereas apo-OVT was detected at the air-water interface owing to the reduced hydrophobicity of air phase. Reduced hydrophobicity of both the protein (apo-OVT) and the dispersed phase (oil) leads to shorter lag periods. As for the interfacial film, holo-OVT formed denser but thinner films than those formed by apo-OVT at both interfaces, as confirmed by larger viscoelastic modulus, reduced film thickness, and lower Gibbs surface excess. These findings were likely attributable to the greater structural rigidity of holo-OVT presented with significant decreases in hydrophobicity index (432.20) than apo-OVT (522.40). Ultimately, holo-OVT exhibited significant improvements in foaming and emulsifying stability than apo-OVT.