Formation of methyl glyoxal in dihydroxyacetone and glycine Maillard reaction: A computational study

By considering the formation of methyl glyoxal as one of the possible intermediates, mechanisms for the intermediate stage of the Maillard reaction of dihydroxyacetone and glycine under different pH conditions have been proposed, following the Hodge-scheme. Density functional theory calculations have been performed at the standard state on the proposed mechanisms to calculated the Gibb's free energy changes for the formation of different compounds in different steps of the reaction. Thus, the possibility for the formation of different compounds in the proposed mechanisms has been evaluated. Electronic energy changes for the formation of different compounds in the proposed mechanisms have been calculated to observe the internal energy changes of the reaction. The total mass balance has been followed during the calculation of electronic and Gibb's free energies. The result reveals that methyl glyoxal is one of the most likely intermediates in the reaction, and dihydroxyacetone + deprotonated glycine and dihydroxyacetone + unprotonated glycine reactions are assumed favorable for the production of methyl glyoxal. The gaseous phase reaction is supposed to be more feasible than the aqueous phase reaction for the production of methyl glyoxal. Glyceraldehyde + protonated glycine and glyceraldehyde + glycine zwitterion reactions are postulated as less feasible for the formation of methyl glyoxal. (c) 2005 Published by Elsevier Ltd.