Nonenzymatic Browning In Liquid Model Systems of High Water Activity: Kinetics of Color Changes Due to Reaction Between Glucose and Glycine Peptides

The rate of browning of solutions (water activity adjusted to 0.90 by adding sodium chloride) of glucose‐glycine peptides (diglycine and triglycine) was well described by a “mixed‐order” kinetic model having two rate coefficients, k o and k l . Activation energies for these parameters were calculated and compared with values for the same reaction of glucose with the amino acid (glycine). At pH below 6 the rate of browning of peptide solutions was higher than that of the amino acid (glycine) at the same molar concentration; at higher pH the reverse was observed.