Safety and Functional Properties of Rapeseed Honey Regarding Its Geographical Origin

Rapeseed (Brassica napus) honey is a popular monofloral honey produced in Poland and is often suspected of pesticide-residue contamination due to the extensive use of pesticides in oilseed rape cultivation. Moreover, because of the presence of fatty acids, it can absorb hydrophobic polycyclic aromatic hydrocarbons (PAHs) that occur as environmental pollutants. Thus, the aim of the study was to assess the safety of rapeseed honey in terms of pesticide residues and PAHs contamination in relation to its functional properties, including antioxidant properties, polyphenol profile, protein content, and enzymatic activity. Local honey samples originating from Lublin (five) and Podkarpackie (five) Voivodeships were compared with five samples purchased from commercial sources. None of 58 pesticides, including carbamates, organophosphorus, organochlorines, pyrethroids, and neonicotinoids, were detected in the tested honey samples. All samples were also completely free of four major harmful PAHs legally limited in food (benzo[a]pyrene, benz[a]anthracene, chrysene, and benzo[b]fluoranthene). Among other PAH compounds, seven were detected accidentally in samples of various origins. The total phenolic content and antioxidant activity determined by DPPH•, FRAP, and CUPRAC assays were relatively uniform among the groups studied. High-performance thin-layer chromatography (HPTLC) revealed characteristic fingerprints including kaempferol, ferulic acid, and caffeic acid, providing a specific profile that can be considered a marker of rapeseed honey authenticity and used to detect adulteration. Protein content ranged from 18 to 85 mg/100 g, remaining within the range typical for light honeys, while α-glucosidase activity was significantly reduced in commercial products, reflecting the effects of processing and storage. The study confirmed the high functional value and safety of rapeseed honey offered on the South-Eastern Poland market, which confirm the cleanliness of the bees’ habitat in terms of pesticide residues and PAHs pollution. Nevertheless, regular monitoring of pesticide residues and PAHs in honeys from agricultural areas remains advisable.