Effect of microwave on fluidized bed drying of macaroni beads

Fluidized bed and microwave assisted fluidized bed drying of macaroni beads were studied using a household microwave oven. Macaroni beads (2.4 ± 0.08 mm diameter), 200 g/batch were dried from about 20% to 12% moisture content. In the experiments with the fluidized bed three air temperatures: 50, 60 and 70 °C at an air velocity of 2.3 m/s and in those with the microwave oven two power levels: 2.1 and 3.5 W/g dry solid were used. Drying rate increased with the air temperature and microwave power. The effective diffusivities in the fluidized bed and microwave assisted fluidized bed drying were found to be in the order of 4.125 × 10−11 and 8.772 × 10−11 m2/s on average, respectively. The effective diffusivities for the fluidized bed drying were fitted to an Arrhenius type of equation.