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The purpose of this study was to predict temperature range in microwave-heated foods, specifically of homogeneous food slabs. To ensure safe heating or reheating of food from a microbiological point-of-view, the minimum temperature achieved within the food should be known.
In microwave heating, the location of the point of minimum temperature is difficult to determine due to the complex heating patterns established within the food. Only by coincidence would a few random temperature measurements within the food hit the point of minimum temperature. To deal with this difficulty, it is beneficial to predict the temperature range within the food. Random sampling of temperature within the food gives an estimate of the maximum temperature. Subtracting the temperature range from the maximum temperature gives a conservative estimate of the lowest temperature. Work under this project succeeded in solving the heat equation, including an energy distribution obtained from the full set of Maxwell equations, for homogeneous foods, under the assumption of slab geometry and temperature-independent thermal and dielectric properties. The solution is a prediction of temperatures as a function of time for any power level of microwave energy. Although the solution is useable in standard spreadsheet software such as Microsoft Excel, further simplifications were accomplished. A modification of this solution was also obtained for the purpose of experimental validation of the model. The project officially ended September 30, 1997 and was not renewed.