Abstract
Bee pollen is a natural nutrient substance collected by bees from plants. Its metabolites have been extensively studied, yet the characteristic metabolites of bee pollen from different floral sources have not been clearly identified. In this study, we collected four types of bee pollen (tea, rose, rapeseed, and corn pollen) from across China and analyzed their volatile and non-volatile metabolites using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and gas chromatography-mass spectrometry (GC-MS). At the same time, the nutritional substances (Including polyphenols, organic acids, and sugars) were precisely quantified. The results showed that the total phenols (5 mg GAE/g) and total flavonoids (0.27 mg RE/g) content of corn pollen were significantly higher (p < 0.05) than those of other pollens, and the contents of polyphenols such as naringenin were relatively high, indicating strong antioxidant potential. Rose pollen was rich in protein (0.04 g/g) and flavonoid glycosides. Tea pollen was prominent in the content of polyphenol glycosides and amino acid derivatives, while rapeseed pollen performed well in phenolic acids (Ferulic acid), as well as specific sugar (Mannose). We identified the differential metabolites of these bee pollen through orthogonal partial least squares discriminant analysis (OPLS-DA) (VIP > 1). It was also stipulated that metabolites with a VIP value greater than 1.5 showed significant differences and could be used as characteristic metabolites for differentiating pollen (p < 0.05). The representative metabolites of bee pollen were as follows: rapeseed pollen-ferulic acid; tea pollen-malic acid; corn pollen-epicatechin; and rose pollen-fumaric acid. This study provides a research basis for evaluating the quality, traceability, and metabolite exploration of bee pollen.