Pre-peeling salicylic acid and post-slicing melatonin treatment: Effects on browning inhibition and quality improvement in lotus root slices

Browning is a major problem in lotus root slices. This study examined the combined effects of pre-peeling salicylic acid (SA) and post-slicing melatonin (MT) on browning inhibition and quality retention. Preliminary tests identified optimal conditions as 3 mM SA for 30 min and 0.1 mM MT for 5 min. Intact roots were treated with SA, slices with MT, or both, and stored at 4 °C for 12 days. The combined SA + MT more effectively maintained visual quality by suppressing polyphenol oxidase and peroxidase activities, preserving firmness via reduced polygalacturonase, β-galactosidase, and cellulase activities, and enhancing antioxidant capacity, total phenolics, and flavonoids. It also lowered H₂O₂ content and lipoxygenase activity, mitigating oxidative stress. Post-slicing MT alone achieved similar browning control but was less effective in texture preservation. These findings indicate that integrated SA and MT application is a promising strategy to extend shelf life and maintain physicochemical quality of fresh-cut lotus root.