Tracking of thermal changes in honey using High-Performance Thin Layer Chromatography

Abstract

PresentationBackgroundHoney is commonly processed prior to packaging, which might involve exposure to elevated temperature inorder to destroy sugar seed crystals that otherwise might accelerate crystallization and / or to removemoisture, filtration to remove debris as well as radiation to destroy spores and pathogens. Heating mighthave a significant effect on the honey{\textquoteright}s phytochemical composition and thus also its bioactivity. It might alsolead to the formation of heat-triggered artefacts such as potentially harmful hydroxymethylfurfural (HMF),which forms as a Maillard degradation product of fructose and other reducing sugars. The monitoring of ahoney{\textquoteright}s composition and bioactivity upon exposure to elevated temperature is therefore of interest to thehoneybee industry.ObjectiveThe objective of this study is to monitor the impact of exposure to a range of elevated temperatures overtime on the phytochemical composition as well as the antioxidant activity of different honeys.MethodologyManuka (Leptospermum spp.), Jarrah (Eucalyptus marginata) and Marri (Corymbia calophylla) honeysalongside an artificial honey (comprised of sugars only) as a comparator were exposed to 40°C, 50°C, 60°C,70°C and 80°C over a period of 48h. Triplicate samples taken at 0 min, 3h, 6h, 12h, 24h and 48h wereanalysed for their antioxidant activity via the DPPH* (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric ReducingAntioxidant Power) assays. Potential changes to the High-Performance Thin Layer Chromatography (HPTLC)derived fingerprints of their organic extracts as well as their HPTLC-DPPH* antioxidant band profiles were alsorecorded. Furthermore, the concentration of HMF in each sample was determined by HPTLC analysis.FindingsThe study demonstrates the impact of heating on the phytochemical composition and antioxidant activity ofdifferent honeys and therefore provides the honeybee industry with useful information on the influence ofprocessing factors on honey quality.