Chitosan-SNAP composite coating with sustained NO release for microbial killing and tomato preservation

Food preservation technologies that combine antimicrobial activity with controlled-release functionality are essential to mitigate postharvest losses. Herein, chitosan (CS)-based coatings incorporating S-nitroso-N-acetyl-DL-penicillamine (SNAP) as a nitric oxide (NO) donor were developed for sustained antimicrobial release and fruit preservation. The CS/SNAP coatings showed high transparency (79.5-79.9 %), strong UV-blocking (T₃₅₀ nm < 1 %), and rapid water solubility, with flexibility increasing alongside SNAP loading. The coatings released NO over 15 days, exhibiting potent antibacterial effects against E. coli (24.64 mm inhibition zone), S. aureus (28.86 mm), and antifungal activity against B. cinerea (20.20 mm). When applied to tomatoes, the CS/SNAP12 coating reduces weight loss, maintains fruit firmness and inhibits ethylene production, thereby extending shelf life to 15 days. Cytotoxicity and seed germination tests confirmed biocompatibility. This scalable, eco-friendly solution synergistically controls respiration, microbial growth, and moisture loss, offering a promising approach to perishable food preservation.