Computational studies on glyceraldehyde and glycine Maillard reaction—III

Abstract

By considering the formation of 2,5-dimethyl pyrazine as one of the possible final product, Density Functional Theory calculations have been performed at the standard state on the proposed mechanisms for the final stage of glyceraldehyde and glycine Maillard reaction under different conditions. Δ G 0 and Δ E 0 of different steps have been calculated by following the total mass balance. Thus, possibility of the formation of different intermediates, and different steps to take place, has been evaluated. Glyceraldehyde+deprotonated glycine reaction has been found to be the most favorable for the formation of 2,5-dimethyl pyrazine in both of the gaseous and aqueous states, and especially in the gaseous state. Glyceraldehyde+unionized glycine reaction favors the formation of 2,5-dimethyl pyrazine mainly in the gaseous phase. Glyceraldehyde+protonated glycine and glyceraldehyde+glycine zwitterion reactions are assumed to be less favorable for the formation of 2,5-dimethyl pyrazine. Aminoacetones have been found to be the most likely precursors for the formation of pyrazine rings. Oxidation plays an important role during the formation of 2,5-dimethyl pyrazine. Water plays an important role for the initiation of both of the gaseous and aqueous phase glyceraldehyde+glycine reactions.