اثر جريان الكتريكي مايكروويوپالسي بر خشك كردن مواد غذايي

Effect of Pulsed Electrical Microwave on Food Stuff Drying

Microwave drying of food stuff has been investigated over several years as a potential means for reducing the total drying time. The material dried by microwave energy has lower quality because of the exitence of non-uniform temperature and moisture distributcons in material, To increase the material quality the pulsed microwave drying was envisaged. In this research mathematical modeling of cramberries drying in a pulsed microwave dryer with on times of 30 and 60 sec and off times of 60-150 sec was carried out. The partial differential equation that was obtained was numerically, solved and moisture and temperature profiles were obtained as a function of time and radius. In general drying was more rapid in the continuous mode than in the pulsed mode. But, the continuous mode required much higher total magnetron power-on times. In the pulsed mode, the longer power-on times generally resulted in slightly faster drying. For a given on-time, an increase in power-off time helps to decrease the total power-on time required for drying. When the microwave oven was operated in a pulsing mode of 30 s power-on and 150 s power-off it resulted in the lowest total power-on time and energy used.