Metal–Phenolic Network–Based Edible Coatings: A New Class of Antimicrobial and Antioxidant Barriers for Fresh Produce Preservation

Abstract

Microbial growth, oxidative reactions, and moisture loss cause fresh fruits and vegetables (F&V) to quickly deteriorate after harvest, reducing their shelf life and market value. Although many current solutions rely on synthetic additives or offer poor functional endurance, edible coatings have been extensively investigated to inhibit these processes. An alternative method is provided by metal-phenolic networks (MPN), which combine naturally occurring phenolic chemicals like gallic and tannic acids with food-grade metal ions like calcium, zinc, or iron. These ingredients work together to create thin, sticky coatings that are suitable for direct contact with fresh produce and have built-in antibacterial and antioxidant properties. Microbial cell membrane rupture, reactive oxygen species scavenging, and a decrease in oxygen and light exposure at the produce surface are just a few of the ways that MPN-based coatings work. Research on berries, oranges, apples, leafy greens, tomatoes, and other F&V shows reduced microbial counts, delayed browning, and better firmness and visual quality retention during storage. Uniform covering and compatibility with current post-harvest handling procedures are made possible by practical coating techniques, such as dip and spray application. Despite these benefits, there are still problems with large-scale processing, regulatory approval, metal ion dosage, and sensory perception. MPN coatings may be able to satisfy commercial needs while promoting safer and more sustainable fresh food preservation with further research into composition management and hybrid formulations.