Analysis of Microwave Heating for Composite Dielectric Food Substances Supported on Ceramic Materials

A detailed theoretical analysis has been carried out to study efficient heating of 1D composite dielectric samples due to microwaves. Current study involves processing of beef with oil layers with/without support and three cases are considered where oil layer is followed by beef layer (case 1), beef layer is followed by oil layer (case 2) and oil-beef layers are exposed to microwaves at both the sides (case 3). For cases 1 and 2, microwaves are incident at the left face only and the support is generally attached with the oil layer. A preliminary analysis has been carried out for beef-oil composite without any support for all cases and it is observed that identical average power in beef sample occurs for small thickness of oil layer irrespective of either oil or beef directly exposed to microwaves (case 1 or 2) and for greater thicknesses of oil layer, the food composite would exhibit greater average power for case 1. The maxima in average power corresponding to resonances occur at various sample thicknesses for all cases with and without supports and two dominant resonance modes R₁ and R₂ are considered where the average power at R₁ mode is greater than that at R₂ mode for all cases. The detailed spatial distribution for various cases illustrates that for small oil thicknesses, heating rate is less and greater heating rate would correspond to larger oil thicknesses. However, the excessive heating in beef sample may correspond to thermal runaway which are also illustrated by ΔT_b (difference between the maximum and minimum values of temperature) in beef samples vs time plot. The similar analysis has been extended for all cases with oil layer directly attached with ceramic supports (Al₂O₃ and SiC). Based on the detailed analysis, the suitability of the support would be guided by factors such as optimal oil thickness, uniform heating and enhanced thermal processing within the beef sample.