Molecular shape analysis of a Maillard reaction intermediate

The Maillard (browning) reaction involving the polycondensation of sugars a nd amino acids is believed to be an important abiotic pathway for humic sub stance formation in nature. However, a major drawback is that the Maillard reaction is extremely slow at temperatures encountered under normal environ mental conditions. In order to elucidate some details of this process molec ular shape analysis was applied to investigate the initial reaction between D-glucose and glycine to form the Amadori compound fructosylglycine which is an intermediate product in the Maillard reaction. The structure of the A madori compound was optimized at a quantum mechanical level and its ground state electron energy calculated. Molecular Iso-Density Contours (MIDCO's), electron density contour surfaces of constant electron density, were const ructed for D-glucose, glycine and fructosylglycine in order to study the st eric conditions for the reaction. The calculations indicate that the Amador i compound and water on one hand and the separate entities D-glucose and gl ycine on the other hand are very similiar to each other in terms of their g round state energy. This agrees with the experimental observation that the reaction between D-glucose and glycine to form the Amadori compound is slow .