Nonenzymatic browning reactions of dihydroxyacetone with amino acids or their esters.

Nonenzymatic browning reactions between dihydroxyacetone (DHA) and amino acids were investigated using buffers as solvents. Regardless of the type of amino acid, DHA was much more reactive than glucose or xylose. Among amino acids tested, lysine was most reactive. The rate of browning was maximum around a DHA-amino acid molar ratio of 1.5, when the total concentration of DHA plus amino acid was constant at 0.1M. When aqueous alcohols were used as solvents, the browning intensity in the reaction between DHA and proline or amino acid ester increased exponentially with a decrease in water content.