Egg white protein-mediated modulation of yogurt gel properties: Physicochemical attributes, structural evolution, and network formation mechanisms

In response to the growing demand for clean-label food products, this study explored the gelling functionality of egg white protein (EWP) as a natural alternative to synthetic thickeners in acid-induced coagulated yogurt. The regulatory mechanism of EWP on yogurt quality was analyzed through physicochemical characterization, microstructural evaluation, and gel network formation. Systematic assessment of egg white (EW) addition (0–50 %) demonstrated that incorporation of 10 % EW significantly enhanced gel properties while maintaining viable lactic acid bacteria counts compliant with national standards. Compared to the control, the 10 % EW formulation exhibited a 12.8 % increase in water-holding capacity, 24.3 % higher hardness, and 34.18 % elevation in storage modulus (G’). Microstructural analysis (SEM), FTIR spectroscopy, and intermolecular force quantification revealed that the composite gel developed a compact three-dimensional network governed by the EWP-casein interaction mechanism: β-sheet conformation formation, hydrophobic interactions, and disulfide bond stabilization. Synergistic cross-linking between hydrophobic forces and disulfide bonds was identified as critical for structural integrity. Flavor analysis confirmed the retention of characteristic dairy-associated compounds (nonanal, 2-undecanone) in the 10 % EW yogurt. This work elucidated the dose-dependent relationship between EW and casein in acid-induced gel systems, providing a scientific foundation for developing yogurts with clean labels and reduced post-acidification.