A kinetic model for the glucose/glycine Maillard reaction pathways

A comprehensive kinetic model for the glucose/glycine Maillard reaction is proposed based on an approach called multiresponse kinetic modelling. Special attention was paid to reactants, intermediates and end products: d-fructose, N-(1-deoxy-d-fructos-1-yl)-glycine (DFG), 1-deoxy-2,3-hexodiulose and 3-deoxy-2-hexosulose, formic and acetic acid, methylglyoxal and 5-hydroxymethylfurfural (HMF). The organic acids were found to be stable end products, 3-deoxy-2-hexosulose was found to be involved in colour formation by reaction with glycine. It is suggested to consider acetic acid as an indicator of the progress of the Maillard reaction at pH 6.8. The significance of reversibility of formation of DFG was studied by kinetic model discrimination. The results suggested that the reaction path from DFG into its parents, glucose and glycine, is not important from a quantitative point of view, even though it does happen. The proposed model was updated and strained by varying one of the most important reaction conditions, the temperature. The estimated rate constants showed an Arrhenius type temperature dependence and the model performed well for all studied temperatures (80, 90, 100, 110 and 120 °C). Striking differences were found in temperature dependencies of the various reaction steps. More than just a fitting procedure, multiresponse modelling was shown to be a powerful tool in unravelling complicated reaction routes as occur in the Maillard reaction.