Metabolomics‐based study of the preservation mechanism of a tea saponin–cinnamaldehyde nanoemulsion applied to Xinyu tangerines

Background The Xinyu tangerine is a geographical indication agricultural product from Jiangxi province, China. During postharvest storage, nutrient loss and pathogen‐induced decay reduce fruit quality. The selection of appropriate preservatives is therefore important for maintaining postharvest quality. Previous studies have shown that tea saponin–cinnamaldehyde nanoemulsion (TS‐CNE) exhibits excellent antifungal activity and physicochemical properties suitable for citrus preservation. This study investigated the preservation efficacy and underlying mechanism of TS‐CNE in Xinyu tangerines using metabolomics. Results The TS‐CNE treatment maintained fruit firmness and color, reduced the decay rate, decreased malondialdehyde (MDA) and H 2 O 2 accumulation in the peel, and increased the total phenolic, flavonoid, and anthocyanin content in the pulp. Untargeted metabolomic analysis showed that the levels of nobiletin, 4′‐methoxyflavanone, kaempferol, neoliquiritin, deoxyloganic acid, xanthohumol, melilotoside, d ‐arabinose, and epigallocatechin in the peel were higher in the TS‐CNE‐treated group than in the control group. Treatment with TS‐CNE can regulate pathways related to adenosine triphosphate‐binding cassette (ABC) transporters, flavonoid biosynthesis, and phenylpropanoid biosynthesis. Conclusion The TS‐CNE treatment effectively preserved postharvest Xinyu tangerines. The preservation mechanism may involve reduced fruit decay during storage through increased accumulation of stress‐responsive metabolites, including flavonoids and phenylalanine, in the peel. These findings provide a theoretical basis for the development and application of TS‐CNE for postharvest disease control in citrus fruit.