Dynamic simulation for radio frequency heating of particle foods: Theoretical development and empirical validation

Abstract. Radio frequency (RF) heat treatment is one of the most promising physical pasteurization and disinfestations methods in low-moisture granular foods. But the major obstacle of RF treatments is non-uniform heating. A computer simulation model using finite element-based commercial software, COMSOL, was developed to help understand RF heating process of particle foods packed in a rectangular plastic container and treated in a 6 kW, 27.12 MHz parallel plate RF system. Spherical soybean particles with the diameter range of 1-5 cm were selected as model material to represent dry granular foods. The developed model based on single particle and simplified air-particle mixture approach was experimentally validated. Both simulated and experimental results showed that the single particle simulation approach was more suitable to characterize and explain the RF heating patterns in large size particle foods (diameter > 1 cm). While for particle foods in small size (diameter ≤ 1 cm), the simplified air-particle mixture approach would achieve good model precision with minimum solution time and less computer resources. With increasing particle diameter, samples placed in corners and edges of the container were more heated and highest temperature values appeared at the contact points for each particle. Horizontal model particle positions with respect to the container and sphere particle diameter significantly influenced the heating patterns inside the model food. The developed model can further be used to study the effect of some important parameters, such as particle shape, structure, composition, and dielectric properties on RF heating of particle foods, and provide valuable information to improve the RF heating uniformity for future industrial applications.