Chemical structure of colored Maillard reaction products

Visual color in processed foods is largely due to colored products of Maillard or nonenzymic browning reactions. In spite of the longstanding aesthetic and practical interest in Maillard-derived food coloring materials, relatively little is known about the chemical structures responsible for visual color. In recent years numerous low molecular weight (<500 Da) colored products have been isolated from model Maillard reactions and their structures elucidated. Many colored products appear to be aldolization/dehydration products of sugars which may or may not be attached to proteins or other sources of amino nitrogen. The structures of high molecular weight Maillard pigments are still mostly undefined, but degradative studies have yielded identifiable fragments with chromogenic properties. This report summarizes the current knowledge of colored compounds formed in the Maillard reaction.