Prolonging fruit shelf-life with a graphitic carbon nitride (GCN) incorporating biopolymer composite: layer-by-layer assembled coating

Abstract

This study presents a novel, biodegradable, and multifunctional layer-by-layer (LbL) coating composed of sodium alginate (SA), chitosan (CAS), and graphitic carbon nitride (GCN) for efficient fruit preservation. The integration of GCN into the SA/CAS matrix significantly enhanced UV shielding, antimicrobial activity, and ethylene scavenging, while maintaining excellent biocompatibility and minimal leaching of GCN. The LbL-coated fruits demonstrated extended shelf life of 15 days for grapes and 10 days for bananas, outperforming uncoated controls. The coating has superior thermal stability, reduced swelling, low moisture permeability, and strong adhesion on irregular fruit surfaces. Importantly, the synergistic action of CAS and GCN delivered over 97% bacterial inhibition, while maintaining cell viability above 90%. These findings establish SA/GCN/CAS/GCN coatings as a safe, scalable, and sustainable alternative to plastic-based packaging. In essence, this is the first report of a GCN-based LbL edible coating that combines biodegradability, antimicrobial performance, UV protection, and fruit shelf-life extension, offering a green solution for modern food packaging challenges.