Color formation Maillard reaction

An effort has also been made to determine the structure of products providing coloration in the Maillard reaction prior to melanoidin formation. The reaction between D-xylose and isopropylamine in dilute acetic acid produced 2-(2-furfurylidene)-4-hydroxy-5-methyl-3(2/f)-furanone (116). This highly chromophoric product can be produced by the combination of 2-furaldehyde and 4-hydroxy-5-methyl-3(2//)-furanone (111) in an aqueous solution containing isopropylammonium acetate. The reaction between o-xylose and glycine at pH 6, under reflux conditions, also pro-duces " 116. Other chromophoric analogs may be present, including 117,... 

The most obvious characteristic is, of course, the formation of a yellow or brown coloration. This becomes progressively darker with time, until it is dark-brown or even black,97 -103 -104 but, if the first step in the Maillard reaction is the formation of the glycosylamine7 - 105 (which is usually colorless48), it is obvious that the rate of color formation alone is not a safe... 

Colour formation is the primary characteristic of the Maillard reaction, yet even now our knowledge of the coloured moieties responsible for the coloration is only rudimentary. 

T. Hofmann, Acetylformoin — a chemical switch in the formation of colored Maillard reaction products from hexoses and primary and secondary amino acids, J. Agric. Food Chem., 1998, 46, 3918-3928. 

T. Knerr, H. Lerche, M. Pischetsrieder, and T. Severin, Formation of a novel colored product during the Maillard reaction of D-glucose, J. Agric. Food Chem., 2001, 49, 1966-1970. 

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