Modulation of protein self-assembly via hydrolysis and metal ion coordination: Effects on EGCG encapsulation and controlled release.

To enhance the stability of EGCG-encapsulated protein carriers under processing and preservation, a zinc-mediated self-assembly strategy was developed. Limited protein hydrolysis combined with cyclodextrin pre-encapsulation was employed to regulate the encapsulation and release of EGCG. Cyclodextrin pre-encapsulation effectively reduced EGCG degradation and loss during particle fabrication. Increasing the protein hydrolysis degree promoted Zn2+-induced coordination and self-assembly, resulting in smaller, more uniform, and compact particles. Cyclodextrin pre-encapsulation improved the encapsulation efficiency of EGCG from average 68.69% to 81.23% and reduced surface-associated EGCG. Compared with free EGCG and samples without Zn2+ (lower than 10%), the strengthened particle structure induced by metal ion showed better stability (maximum 75.1% of EGCG retention rate) after 24 h of alkaline incubation. During simulated digestion, the release of EGCG was delayed until the late intestinal phase and reached maximum 46.53% of EGCG bioaccessibility. Moderate protein hydrolysis and metal-induced self-assembly is a potential strategy to optimize EGCG encapsulation and release in protein-based delivery systems.