Fate of glycine in the glucose-glycine reaction: a kinetic analysis

The behaviour of glycine was studied in its reaction with glucose at pH 6.8 between 80 and 130degreesC. Glucose reacted more strongly than glycine, which was due to two phenomena: (i) besides its participation in the Maillard reaction, glucose also isomerizes into fructose and (ii) intact glycine is released from the initial Maillard condensation products in the intermediate phase of the reaction. From 80 to 100degreesC, the loss of glycine could be completely accounted for in the Amadori product (ARP) and the melanoidins. At higher temperatures, a small loss occurred (10-20% of the initial glycine concentration) probably due to formation of Strecker reaction products. The behaviour of glycine is such that the kinetics of its decrease in the Maillard reaction cannot be taken as a measure for the progress of the Maillard reaction. (C) 2002 Elsevier Science B.V. All rights reserved.