Moisture transport in garlic cloves undergoing microwave-convective drying

A laboratory scale microwave dryer was used to dry the garlic cloves, applying microwave power in the range of 10-40 W, air temperature in the range of 40-70 degrees C and air velocity in the range of 1.0-2.0 m/s. Heat and mass transfer coefficient during the drying process varied in the range of 35.23-79.54 W/m(2)C and 4.26-6.34 x 10(-2) m/s. The temperature of the product rose rapidly in the early part of the drying and became almost stable thereafter. The Biot mass transfer number confirmed that moisture diffusion was the limiting factor in microwave drying of garlic. The effective moisture diffusivity, which ranged between 1.29-31.68 x 10(-10) m(2)/s increased with the increase in microwave power but decreased with increase in air velocity. (c) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.