Novel insights into interfacial effects on α, β-unsaturated aldehyde-induced modifications of milk proteins and polyphenol interventions in multiphase food systems

Lipid peroxidation remains an inevitable challenge during dairy processing and storage. The α, β-unsaturated aldehydes produced during lipid peroxidation are highly reactive with proteins, which can degrade the stability and nutritional quality of dairy products. Polyphenols are widely used as antioxidants to control degradation caused by α, β-unsaturated aldehydes. However, most studies focus on homogeneous systems, overlooking the influence of the complex interfaces inherent in dairy products on protein modification by α, β-unsaturated aldehydes and the intervention of polyphenols. Herein, we established a Hex-milk protein interfacial model system and employed clickable probes (yne-ACR) to simulate the modification of milk proteins by α, β-unsaturated aldehydes. Additionally, six polyphenols with different structures were added to intervene the modification by yne-ACR. Results demonstrated that both yne-ACR modification and the intervention of different polyphenols significantly altered the dynamic interfacial behavior and expansion rheological properties of milk proteins. However, the impact on the stability of the interface model system was minimal. Notably, casein in milk proteins predominantly adsorbed at the interface. The in-gel fluorescence imaging revealed that the presence of the interface enhanced the modification of milk proteins by yne-ACR. The intervention effects of polyphenols varied based on their structural characteristics: PA, GA, GeA, RA, and EC inhibited the modification of non-adsorbed β-lactoglobulin (β-Lg) by yne-ACR, while EGCG significantly suppressed yne-ACR modification of both interfacial and non-adsorbed proteins and notably reduced protein carbonylation. This study highlights the critical role of interface microenvironment in influencing α, β-unsaturated aldehyde-protein interactions and analyzes the intervention effects of polyphenols with varying structures in complex food systems. These findings provide a theoretical foundation for the rational use of antioxidant strategies in dairy processing.