Spectrophotometric determination of 5-hydroxymethylfurfural in honey samples of various botanical origins

Abstract

Improper processing, storage conditions, or adulteration of honey promotes the formation of 5-hydroxymethylfurfural (HMF). HMF is detrimental to human health if the consumption level exceeds the limit established by regulatory bodies. The Codex Alimentarius Commission and the European Union have set the HMF limit in honey at 40 mg/kg, with a higher limit of 80 mg/kg for countries or regions with tropical temperatures. The International Honey Commission recommends three methods for HMF determination: two spectrophotometric methods (the White method and the Winkler method) and High-Performance Liquid Chromatography (HPLC). However, the regulated Winkler method is predominantly used for HMF determination in research conducted in Ukraine. In this study, 17 honey samples collected between 2022 and 2025 and having various botanical origins were analyzed using the White method. This method is based on the cleavage of the HMF chromophore system by the action of sodium metabisulfite. The difference in light absorption at a wavelength of 284 nm between the honey sample treated with metabisulfite and the untreated sample is proportional to the HMF concentration. To eliminate the effects of light scattering and light absorption by the honey matrix, measurements were conducted at two wavelengths: 284 nm and 336 nm. Monofloral honey samples (sunflower, linden, acacia, rapeseed, and amaranth), polyfloral wildflower honey, and blended honey samples were analyzed. The HMF content in almost all tested honey samples was significantly lower than the recommended limit. The lowest HMF content was found in monofloral honeys such as linden and sunflower, ranging from 0.63 to 2.8 mg/kg. A slightly higher HMF content was observed in acacia honey samples, ranging from 10.8 to 14.6 mg/kg. The HMF content in polyfloral wildflower honey and blended honey samples fell within the same range. Analysis of sunflower, rapeseed, and amaranth honey harvested in 2025 demonstrated that their HMF content was significantly below the normative values.