Numerical study of initially frozen rice congee with thin film resonators package in microwave domestic oven

Packaging plays a crucial role in microwave processing of foods. However, the characteristics of frozen food and the resonance package are not well understood and inadequate. In this work, the approach is mainly based on a coupled electric‐thermal model. The numerical model of the microwave heating of frozen rice congee with resonance package is developed using COMSOL Multiphysics 4.4 software to examine the effects of metal film as a resonator and the port power position on heating patterns and rates in domestic microwave oven. The simulation model food of stationary is placed in the center of the domestic microwave oven. The sample is heated from the room temperature for 60 s, 800 W, and 2.45 GHz. The dielectric properties are measured as a function of the temperature and the thermal properties are calculated from chemical composition of frozen rice congee. In order to validate the results of simulation, a series of experiments were performed with three replicates at each case. The temperature is recorded using fiber‐optic sensors and thermal imaging camera. The results show good agreement with simulated results. The difference in results is found by 5–10%. The results in this work indicate that the temperature of frozen food after subjected to microwave is highest in case no metal film on package for both top and side port power. Further investigation showed that the metal film area on package affects heating uniformity. The top port power increases more than 25% of sample temperature. PRACTICAL APPLICATIONS: The popularity of microwave ovens has led food producers to develop a new generation of microwave heating products. Many products can be heated and served in their packages. However, the big problem in the microwave heating of food is nonuniform heating. The metal microwaveable packaging is developed as one solution of how to overcome this problem. The reason is that the metal film can change the electric distribution pattern because of changing heating profile. This work examines the effects of metal film area and port power position on heating uniformity and thawing time in microwave process. The application of this work can be used to optimize the port position and food package modification to achieve more uniform heating.