Preparation and functional characteristics of Lactobacillus plantarum encapsulated by metal phenolic network coatings

Metal-phenolic networks (MPNs) exhibit rapid film formation and surface modification potential, but their material selection and mechanisms are insufficiently explored. This study used gallic acid (GA), epigallocatechin (EGC), and epigallocatechin gallate (EGCG) as polyphenol precursors to construct MPNs coatings on Lactobacillus plantarum ( L. plantarum ) via coordination with ferric (Fe 3+ ) or calcium (Ca 2+ ) ions. Systematic analysis showed that polyphenol structure and metal ion (Fe 3+  > Ca 2+ ) significantly affect coating performance, with EGCG-Fe 3+ coatings achieving the greatest thickness (1584 nm), strongest metal-phenolic coordination, and highest stability. This coating also demonstrated remarkable functional enhancements: superior antioxidant capacity (75.9% DPPH and 98.96% ABTS scavenging rates), high antibacterial rate (78.7%), and excellent gastrointestinal tolerance, maintaining viable cell counts above 10 7  CFU/mL throughout digestion stages. These findings clarify MPNs formation mechanisms, laying a theoretical basis for optimizing polyphenol-metal coordination in probiotic encapsulation systems to enhance functionality and expand applications in probiotic food development.