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

Presentation
Background
Honey is commonly processed prior to packaging, which might involve exposure to elevated temperature in
order to destroy sugar seed crystals that otherwise might accelerate crystallization and / or to remove
moisture, filtration to remove debris as well as radiation to destroy spores and pathogens. Heating might
have a significant effect on the honey’s phytochemical composition and thus also its bioactivity. It might also
lead 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 a
honey’s composition and bioactivity upon exposure to elevated temperature is therefore of interest to the
honeybee industry.
Objective
The objective of this study is to monitor the impact of exposure to a range of elevated temperatures over
time on the phytochemical composition as well as the antioxidant activity of different honeys.
Methodology
Manuka (Leptospermum spp.), Jarrah (Eucalyptus marginata) and Marri (Corymbia calophylla) honeys
alongside 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 were
analysed for their antioxidant activity via the DPPH* (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric Reducing
Antioxidant 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 also
recorded. Furthermore, the concentration of HMF in each sample was determined by HPTLC analysis.
Findings
The study demonstrates the impact of heating on the phytochemical composition and antioxidant activity of
different honeys and therefore provides the honeybee industry with useful information on the influence of
processing factors on honey quality.