Determination of the degradation kinetics of anthocyanins in a model juice system using isothermal and non-isothermal methods

The effect of temperature on the degradation of blackcurrant anthocyanins in a model juice system was determined over a temperature range of 4-140 degrees C. The thermal degradation of anthocyanins followed pseudo first-order kinetics. From 4-100 degrees C an isothermal method was used to determine the kinetic parameters. In order to mimic the temperature profile in retort systems, a non-isothermal method was applied to determine the kinetic parameters in the model juice over the temperature range 110-140 degrees C. The results from both isothermal and non-isothermal methods fit well together, indicating that the non-isothermal procedure is a reliable mathematical method to determine the kinetics of anthocyanin degradation, The reaction rate constant (k) increased from 0.16 (+/- 0.01) x 10(-3) to 9.954 (+/- 0.004) h(-1) at 4 and 140 degrees C, respectively. The temperature dependence of the rate of anthocyanin degradation was modelled by an extension of the Arrhenius equation, which showed a linear increase in the activation energy with temperature. (C) 2008 Elsevier Ltd. All rights reserved.