Chemometric dissection of typical tropical rambutan: revealing the unique metabolite profiles

The physicochemical properties, antioxidant activities, and metabolomic differences of three typical tropical rambutan varieties (BY-4, BY-5, and BY-7) were characterized in this study based on metabolomics and chemometrics approaches. BY-7 showed a significant advantage, with higher total soluble solids (TSS) than BY-4 (2.10 %) and BY-5 (2.42 %). The total phenol of BY-7 was 1.38-fold and 1.20-fold higher than that of BY-4 and BY-5, respectively. The antioxidant activities of 2, 2-diphenyl-1-picrylhydrazy, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid), and ferric reducing antioxidant power were BY-7 > BY-5 > BY-4. Adipic acid in BY-4, vanillic acid in BY-5, and (+)-catechin in BY-7 as key differential metabolites were species-specific. The galactose metabolism as a core regulatory pathway was revealed by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. This suggests that differences in galactose metabolism among varieties may significantly influence sugar accumulation (contributing to higher TSS in BY-7) and potentially serve as precursors or regulators for the synthesis of phenolic compounds (linked to BY-7's superior antioxidant capacity). This study revealed the unique metabolite profiles of typical tropical rambutan based on chemometric dissection, and provided a new direction for the study of rambutan functional components.