Exogenous melatonin preserves quality and inhibits browning of fresh‐cut feijoa through regulation of oxidative stress and phenylpropanoid metabolism during cold storage

BACKGROUND In recent years, the increasing demand for healthy, convenient, and ready‐to‐eat food has led to fresh‐cut fruit becoming increasingly popular. However, mechanical damage during processing accelerates deterioration, resulting in browning, ‘off’ flavors, softening, and reduced shelf life. RESULTS Treatment with 0.2 mmol L −1 melatonin (MT) delayed onset of browning significantly (observed on day 6 versus day 2 in controls), reduced weight loss, and preserved higher total soluble solids (TSS). Melatonin treatment also slowed sucrose decline and minimized the degradation of succinic and tartaric acids, preserving flavor stability. The application of MT suppressed lipid peroxidation, as shown by 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays, through elevated phenolic compound content (gallic acid, catechin, and epigallocatechin). Melatonin promoted phenolic biosynthesis by increasing the activity of phenylalanine ammonia‐lyase (PAL) and chalcone synthase (CHS), while inhibiting polyphenol oxidase (PPO)‐mediated browning. CONCLUSION Melatonin treatment could be a viable postharvest strategy for fresh‐cut feijoa and other perishable fruits during cold storage. These results establish the use of MT as a viable postharvest strategy for fresh‐cut feijoa and other perishable fruits.