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.