Modeling of heat and mass transfer and drying characteristics of sliced food with microwave drying

In order to understand the behavior of sliced food during microwave drying, the microwave drying characteristics of sliced food were investigated experimentally and numerically using potatoes as test samples. The temperature variations and drying characteristic curves during the drying process were obtained. The effects of sample thickness and microwave power level on the drying process were discussed. Using heat balance and diffusion theory, the modeling equations for temperature and moisture changes were developed and solved, which gave the results in good agreement with the experimental ones. It indicates that sliced food experienced three periods during microwave drying: a pre-heating period with little removal of moisture, a constant temperature period in which most moisture loses and food temperature depends on microwave power level and sample thickness, and a quick heating period with drying rate dropping off and sample temperature rising rapidly. It is also found that drying rate increases with the microwave power levels, but is not affected by sample thickness.