L-ascorbic acid in nonenzymatic reactions. I: Reaction with glycine

The influence of the water content, molar ratio, time and temperature on the formation of nondialysable melanoidins produced by the interaction of L-ascorbic acid and glycine has been studied. The isolated polymers have been characterized by spectrum analysis and fractionated using gel chromatography. The rate constants of the reaction for temperatures of 90 degrees C, 100 degrees C and 110 degrees C have been calculated and are (0.84 +/- 0.29) x 10(-5) x s-1, (1.33 +/- 0.14) x 10(-5) x s-1 and (5.30 +/- 0.37) x 10(-5) x s-1, respectively. The activation energy of the reaction has been determined to be 106.07 +/- 32.47 kJ/mol.