Identification and characterization of plant-derived biomarkers and physicochemical variations in the maturation process of Triadica cochinchinensis honey based on UPLC-QTOF-MS metabolomics analysis

The maturation patterns of nectar into honey are not well understood. The current work selected Triadica cochinchinensis honey (TCH) at three maturity stages to systematically investigate the variation patterns in physicochemical parameters and metabolites. Based on both targeted and untargeted metabolomics analyses, the N1, N5, N10-(E)-tricoumaryl spermidine was identified as the plant-derived characteristic compound in TCH. A total of 26 compounds were quantified by UPLC-QTOF-MS using an external standard calibration method. Two patterns of the honey maturation process were identified based on the 723 metabolite signature transformations. The first was that the levels of plant-derived compounds with strong reducing activity were reduced, such as spermidine, flavonoids, and their derivatives. In contrast, the second pattern was that the maturation process of honey was accompanied by the formation of lactone glycoside analogs and organic acids, which may be facilitated by the enzymatic transformation of enzymes secreted by the bees.