Mathematical modeling of ohmic heating of two-component foods with non-uniform electric properties at high frequencies

Abstract

Abstract The ohmic heating (OH) of two-component foods (consisting of mashed potato and mashed potato with 1% NaCl) configured using four different filling patterns (parallel, series, and two concentric patterns) was investigated experimentally and by modeling. The electrical conductivities of the samples at 50 Hz and 20 kHz were obtained in the range of 20–85 °C. The differences between the thermal behaviors of the two-component foods were analyzed using internal thermal images and temperature profiles from four positions. A three-dimensional OH model for high frequencies was developed based on electric field analysis using Maxwell's equations. The model agreed sufficiently with the measured results and was able to confirm that the current applied to the sample follows the path that presents minimum electrical resistance, which is independent of the filling pattern configuration. Analysis of the heat flux density provided a better understanding of the heating behavior of two-component foods during OH. Industrial relevance Although several mathematical approaches used to simulate the OH process of solid foods have been published in recent years, the simulation of temperature and electric field distributions using simplified methods, such as by the solution of Laplace's equation, is still a problem for two-component solid foods with special configurations of the internal components treated using an OH process at high frequencies. This problem can be solved using a more fundamental solution based on Maxwell's equations and electric field analysis via computer simulation. A comprehensive mathematical simulation of the thermal behavior and the effect of the orientation of the current within the two-component foods can be used to accurately predict the heat during OH. Therefore, the modeling of heating patterns of complex foods can assist in the design of food sterilization and pasteurization processes. Moreover, it will contribute in industrial applications for a better design of OH systems and electrode configurations for rapid and uniform heating.