Impact of pH on the kinetics of acrylamide formation/elimination reactions in model systems

The effect of pH on acrylamide formation and elimination kinetics was studied in an equimolar (0.1 M) asparagine-glucose model system in phosphate or citrate buffer, heated at temperatures between 120 and 200 degrees C. To describe the experimental data, a simplified kinetic model was proposed and kinetic parameters were estimated by combined nonlinear regression and numerical integration on the data obtained under nonisothermal conditions. The model was subsequently validated in a more realistic potato-based matrix with varying pH. By increasing acidity, the reaction rate constants at T(ref) (160 degrees C) for both acrylamide formation and elimination can significantly be reduced, whereas the temperature dependence of both reaction rate constants increases. The introduction of a lyophilized potato matrix (20%) did not affect the acrylamide formation reaction rate constant at reference temperature (160 degrees C) as compared to the asparagine-glucose model system; the elimination rate constant at T(ref), on the contrary, was almost doubled.