A new approach to study the significance of Amadori compounds in the Maillard reaction

A new approach to study the significance of Amadori compounds in the Maillard reaction involves a comparison of their rates of reaction with sulphite species, S(IV), with the rates of reaction of S(IV) in the corresponding reducing sugar-amino acid-S(IV) reactions. The rate of formation of monofructoseglycine, MFG, in the glucose-glycine-S(IV) reaction ([glucose] = 1 M, [glycine] = 0.5 M, [S(IV)] = 0.05 M, pH 5.5, 55 degrees C) in 0.2 M acetate buffer is 30 x 10(-5) mol l(-1) h(-1) and the rate of loss of S(IV) of the order 8 x 10(-5) mol l(-1) h(-1). The concentration of MFG increases to 40 mM by the time all the S(IV) has undergone reaction. On the other hand, the reaction of MFG with S(IV) is immeasurably slow (< 1 x 10(-5) mol l(-1) h(-1) when [MFG] = 10-40 mM, [Glycine] = 0.5 M, [S(IV)] = 0.02 M), under the same conditions. The rate of browning of MFG, MFG-glucose and MFG-glycine mixtures was found to be much slower than the rate of browning in the corresponding glucose-glycine reaction. This evidence all points to the noninvolvement of MFG in the glucose-glycine Maillard browning reaction during the stage where S(IV) exerts its inhibitory effect. Copyright (C) 1996 Elsevier Science Ltd.