Abstract: With the aim of identifying the differential metabolic pathways in peanut skins of different varieties, non-targeted metabolomic analysis of peanut skins with different colors was performed by liquid chromatography-mass spectrometry. Principal component analysis (PCA) showed that there were significant metabolic differences in peanut skins with different colors. Totally 16 differential metabolites were separated according to the variable importance in the projection values from the orthogonal partial least squares discriminant analysis (OPLS-DA). The contents of kaempferol and catechin-(4α→8)-gallocatechin-(4α→8)-catechin as well as the contents of proanthocyanidins, myricetin and quercetin were significantly higher in peanut skins with a darker color (P < 0.05). The differential metabolites were enriched in four metabolic pathways. The flavone and flavonol biosynthesis pathways were the most significant among the metabolic pathways, in which kaempferol, quercetin, myricetin and rutin were involved. Kaempferol was actively metabolized in peanut skins with a darker color, while myricetin and quercetin were actively metabolized and synthesized in larger amounts in peanut skins with a lighter color.

Key words: peanut skins, color, metabolomics, differential metabolites, metabolic pathway