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United States Department of Agriculture

Agricultural Research Service

Research Project: NEW TECHNOLOGIES TO PROCESS VALUE-ADDED, HEALTHY FOODS FROM FRUITS AND VEGETABLES Title: Multiphysics modeling of microwave heating of whole tomato

Authors
item Milczarek, Rebecca
item McHugh, Tara

Submitted to: Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: February 18, 2010
Publication Date: July 18, 2010
Citation: Milczarek, R.R., Mc Hugh, T.H. 2010. Multiphysics modeling of microwave heating of whole tomato. Institute of Food Technologists.

Technical Abstract: A mathematical model of a food is useful for prediction of temperature profiles during microwave heating. However, due to their complex geometry and interaction with electromagnetic fields, whole tomatoes resist an analytical approach to modeling the fruit as it is subjected to microwave energy. The objective of this research was to use a multiphysics (heat transfer and solving of Maxwell’s equations) computational approach to model the temperature changes within a whole tomato as it is heated in a microwave oven. A three-dimensional model of a Roma tomato was designed in a commercial multiphysics software environment. The model included the thermal and dielectric properties of the fruit. A 2450 MHz, 1300 W household microwave oven was also modeled. Heat transfer and electromagnetic energy were coupled in the simulation, and predictions for point temperature measurements were generated in the model. Twelve tomatoes whose geometry and composition were similar to the model fruit were heated in a microwave oven for ten seconds each. Fiber optic temperature probes tracked the temperature changes at a total of twenty-five points throughout the fruit. Compared to the experimental results, the multiphysics simulation tended to underpredict temperature. Average error rates began high but decreased to less than half their initial values by the end of heating, indicating better performance of the model under linear temperature change conditions. Both the computational and experimental results showed that the effects of the geometry of the tomato fruit and the microwave oven contributed to uneven heating of the fruit along the axis of microwave transmission. This indicates that, to control the heating pattern inside a microwaved tomato, one should adjust geometric parameters of the system. This multiphysics model will be used to facilitate design of novel microwave processes for tomatoes and other whole fruit.

Last Modified: 10/21/2014