Relative reactivities of glucose and galactose in browning and pyruvaldehyde formation in sugar/glycine model systems

Glucose/glycine and galactose/glycine model systems were incubated at 45 and 60 °C for the studies of Maillard browning, sugar consumption, and pyruvaldehyde formation. The results showed that, at pH 8, rates of browning followed pseudo-zero-order kinetics. Sugar consumption followed two-staged first-order kinetics with a lower rate constant at the second first-order stage when initial sugar concentration was 2.4% w/v and higher. The yield of pyruvaldehyde followed a third-ordered function of time. Although galactose/glycine system browned at a faster rate, glucose consumed faster than galactose in model systems. The yield of pyruvaldehyde was higher in galactose/glycine systems than in glucose/glycine systems at 45 °C, but inverted at 60 °C.