Kinetics of Crude Peroxidase Inactivation and Color Changes of Thermally Treated Seedless Guava (Psidium guajava L.)

Thermal treatment of seedless guava (Psidium guajava L.) cubes was carried out in the temperature range of 80-95 degrees C. The kinetics of peroxidase inactivation and color changes due to thermal treatments were determined. Peroxidase inactivation followed a first-order kinetic model, where the activation energy was 96.39 +/- 4 kJ mol(-1). Color was quantified in terms of L, a, and b values in the Hunter system. The color changes during processing were described by a first-order kinetic model, except total color difference which followed a zero-order kinetic model. The temperature dependence of the degradation followed the Arrhenius relation. The activation energies (E-a) for L, a, b, and total color difference (Delta E) were 122.68 +/- 3, 88.47 +/- 5, 104.86 +/- 5, and 112.65 +/- 5 kJ mol(-1), respectively. The results of this work are a good tool to further optimize seedless guava thermal treatment conditions.