Radio frequency heating uniformity evaluation for mid-high moisture food treated with cylindrical electromagnetic wave conductors

Non-uniform heating is an important obstacle for applying radio frequency (RF) energy in food processing, especially for the material with high moisture content. To further extend wide applications of the RF heating uniformity improvement based on our previous study with cross electromagnetic wave conductor (EWC), a novel and effective method with cylindrical electromagnetic wave conductors and cylindrical containers was introduced in this study to improve the electromagnetic energy distribution inside the sample with mid-high moisture content. The associated computer simulation model with cylindrical EWC and container was also developed and validated based on RF experimental results to evaluate the heating uniformity. The results showed that the parameters of EWC (diameter and height) had a positive effect on the RF heating uniformity index. The sample treated with cylindrical EWC had better heating uniformity but lower temperature than that treated with cross EWC based on the comparison results. The improved target uniformity index (TUI) and the decreased heating time also indicated the positive effects of cylindrical EWC. A simplified structure for cylindrical EWC was developed and evaluated by computer simulation, which may provide potential applications of the cylindrical EWC to achieve the required RF heating uniformity in mid-high moisture food.