Computational evaluation of food carrier designs to improve heating uniformity in microwave assisted thermal pasteurization

Microwave assisted thermal pasteurization system (MAPS) is a novel food safety technology that employs carriers made from stainless steel to move pre-packaged foods inside 915 MHz single mode microwave cavities to eliminate bacterial and viral pathogens. This paper studied the performance of metal carriers for 16 oz and 10 oz food packages in the MAPS. A simulation model built with Quick-wave software was developed to analyze the electromagnetic field distribution inside a MAP system as affected by the presence of the metal food carriers. Computer simulations were validated using a mashed potato model food processed in a pilot scale MAP system; heating patterns of the samples were detected by a chemical-marker based computer vision method. Results showed that different designs of the food carriers could be used to modify electric field distribution to obtain relatively uniform heating patterns within the microwave cavities. Simulation results also illustrated that magnetron frequency variations between 900 MHz and 920 MHz do not affect the heating patterns of food packages processed using carriers containing metal parts. The results demonstrated that the MAPS with moving metal carriers has stable and predictable heating patterns.