The Preserving Effect of a Lemon Essential Oil‒Rutin‒Chitosan Composite Coating on Seasoned White Snakehead Fillets and Dynamic Changes in Metabolites

In this study, we investigated the preservation efficacy of a lemon essential oil-rutin-chitosan (CS-LEO/NE-R) composite coating on seasoned white snakehead fillets and systematically evaluated dynamic metabolite changes via untargeted metabolomics. The results demonstrated that the composite coating significantly (p < 0.05) suppressed microbial proliferation while delaying increases in pH, total volatile basic nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS), thereby extending the microbial spoilage threshold by 5 days. Untargeted metabolomics identified 2271 metabolites, with differentially abundant metabolites predominantly involving amino acids and their derivatives, organic acids and their derivatives, and glycerophospholipids. KEGG enrichment analysis suggested that the composite coating maintained cellular membrane stability and was associated with alterations in glycerophospholipid, arachidonic acid, and linoleic acid metabolism pathways linked to membrane integrity, enhanced antioxidant defences, and regulation of energy metabolism homeostasis. Concurrent enrichment of α-linolenic acid metabolism further pointed to altered fatty acid metabolism, consistent with reduced lipid peroxidation product accumulation.