Kinetics of conversion of dihydroxyacetone to methylglyoxal in New Zealand mānuka honey: Part I – Honey systems

•Overall loss of DHA and early stage formation of MGO is first order.•In mānuka honey later stage kinetics of MGO formation are complex.•Lower storage temperature gives better efficiency of DHA conversion to MGO.•Proline and phenyllactic acid are correlated with the rate constant for DHA loss.•The rate may be controlled by a proportion of DHA existing in the dimeric form. The kinetics of conversion of dihydroxyacetone (DHA) to methylglyoxal (MGO) were investigated in mānuka honeys and DHA-doped clover honeys stored between 4 and 37°C. Both the disappearance of DHA and appearance of MGO were confirmed as overall, first order reactions, albeit probably composites of multiple reactions. Increasing the storage temperature accelerated the rate of DHA loss and the initial rate of formation of MGO, but better conversion efficiency was observed at lower temperature. At 37°C, more MGO was lost at later times in mānuka honey compared to DHA-doped-clover honey. Thirty-seven New Zealand mānuka honeys and four clover honeys were analysed for various chemical and physical properties; comparison of rate constants and these parameters identified some positive correlations.