(-)-Epigallocatechin-3-Gallate (EGCG) Regulates the Formation of Zein-Ovalbumin Heteroprotein Complex Coacervates

Growing interest in sustainable nutrition has improved the importance of understanding the interactions between (-)-Epigallocatechin-3-gallate (EGCG), a polyphenol in green tea, and proteins for functional food development. In this study, we investigated the regulatory effects of EGCG on the aggregation behavior of zein, ovalbumin, and their complexes. The addition of EGCG at 100 μg mL^-1 led to significant changes in particle sizes of zein, ovalbumin, and zein-ovalbumin complexes, increasing them from 215.6, 3485.3, and 2081.0 nm to 4822.3, 7857.0, and 5895.7 nm, respectively. The zeta potentials of these samples decreased from 8.4, -2.6, and 5.0 mV to -5.3, -0.66, and 2.13 mV, respectively, indicating a reduction in net surface charges and promotion of protein aggregation. UV-vis absorption spectroscopy revealed hyperchromic effects and blue shifts upon EGCG addition, suggesting conformational changes. Molecular dynamics simulations further revealed that EGCG contributed to the structural stabilization of both individual proteins and their complexes by reinforcing hydrophobic and electrostatic contacts at the molecular interface. These findings provide molecular-level insights into the regulatory role of EGCG in protein assembly and offer guidance for the rational design of plant-animal protein complexes with tailored functional properties for food applications.