Comprehensive metabolite profiling reveals biochemical evolution in coconut water during fruit development

In this study, Wenchang Sweet Coconut (Cocos nucifera L. 'Wenchang-Sweet') was selected as the experimental material, with Hainan Tall Coconut (Cocos nucifera L. 'Hainan-Tall') water served as the control. Changes in key secondary metabolites—includingphenolic acids, alkaloids, terpenoids, lignans, and coumarins—in coconut water were analyzed across six maturity stages (I to VI, corresponding to 2, 4, 6, 8, 10, and 12 months of age). Metabolite profiling and differential screening were performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with a metabolomics approach. The results showed that 168 secondary metabolites were identified in the coconut water of both HTC and WSC, comprising 120 phenolic acids, 26 alkaloids, 6 terpenoids, 12 lignins and 4 coumarins. During the ripening process, the content of secondary metabolite in the coconut water declined in of both HTC and WSC coconuts, however, WSC consistently exhibited significantly higher levels. The number of differentially expressed secondary metabolites between WSC and HTC at each ripening stage was 78, 47, 54, 68, 80, and 62, respectively. Key metabolites such as Choline, Chlorogenic acid and Caffeic acid were identified, along with 30 characteristic secondary metabolites. KEGG pathway enrichment analysis revealed that secondary metabolites were primarily enriched in eight metabolic pathways including aminobenzoate degradation (ko00627), phenylpropanoid biosynthesis (ko00940) and biosynthesis of various plant secondary metabolites (ko00999). This study provides a strong theoretical foundation for functional research and product development related to coconut secondary metabolites.