Dehydration Characteristics of Taro Root (Colocasia Esculenta) Slices using a Refractance WindowTM Dryer

Abstract

This report presents the dehydration characteristics of Taro (Colocasia esculenta) root slices dried at 65, 75, 85 and 95oC in a fabricated laboratory scale Refractance WindowTM dryer; the Taro root slices were 3.0, 4.5 and 6.0 mm thick. Moisture content and water activity variation data were taken during the drying operation for the process conditions selected. For the process conditions studied, the times required to dehydrate the moisture content to 0.11 g-water/g-solid varied between 55 to 260 minutes. For a given slice thickness, the drying times to reach the 0.11 g-water/g-solid moisture content decreased as the drying temperature increased. Also, for a given drying temperature, the drying times required to reach the 0.11 g-water/g-solid moisture content increased with slice thickness. The effective moisture diffusivity varied from 8.14 x 10-08 to 9.53 x10-07 m2/s for the process conditions studied. While moisture diffusivity data on the Refractance WindowTM dryer, was not found in the literature, the moisture diffusivity values estimated, were within the range observed for other equipment. The moisture diffusivity parameters determined in this study, are important because they are useful in the design, modelling, and optimisation of such dryers.