Numerical modeling of peroxidase inactivation in potato tubers

The properties of peroxidase (POD) inactivation in potato during hot water heating were studied. In the conventional method, the vegetable sample is heated at a constant temperature, and the POD inactivation rate at each temperature is obtained. The activation energy and frequency factor are then calculated from Arrhenius plots of the inactivation rates. Although only the temperature of the hot water is used in the calculation, the actual potato sample temperature is not considered. In this study, unequal temperature distributions in a potato cylinder during hot water heating were simulated by a finite element method using COMSOL Multiphysics. In this simulation, thermal conductivity of the potato tuber was determined to fit best with the measured temperature as λ = (-3.1 × 10^-5)T2 + (1.8 × 10^-2)T × 1.9. Additionally, POD inactivation was predicted based on the simulated temperature distribution. The activation energy and frequency factor were then determined as 29.2 kJ mol-1 and 2.0 × 102 s^-1 to minimize the root mean square error between predicted and measured POD activities. The adequacy of these parameters was confirmed using a validation test with a potato cylinder of a different size. It was concluded that finite element method simulation was valid for determining the POD inactivation property.