Numerical analysis of rectangular type batch ohmic heater to identify the cold point

The objective of this research was to precisely simulate the temperature distribution and inactivation of Escherichia coli O157:H7 by batch ohmic heating pasteurization of orange juice based on a time-dependent numerical model. A finite element method (FEM) embedded with pathogen inactivation codes using Java language simultaneously solved electric heating, k-ε turbulent flow, and heat transfer equations and dealt with natural heat losses through the walls and air as the boundary conditions. The simulated temperature distribution and populations of E. coli O157:H7 did not differ from the experimental data for every treatment time within a relative error of 6.0%. A cold point problem was observed in the bottom corner, which was more severe for large orange juice samples, leading to an increased treatment time in order to ensure a 5-log reduction of E. coli O157:H7.