Effect of thickness and pre-treatment on drying kinetics of cocoyam

Abstract

Cocoyam (Xanthosoma sagittifolium) corms and cormels are among the staple foods in Nigeria. The cormels are processed into cocoyam flour and utilized for various purposes. Drying is an essential unit operation in the conversion of the cormels into cocoyam flour and the knowledge of the effect of drying variables on the drying characteristics of the cormels is necessary for analysis, optimization and control of the drying process. This study therefore, investigated the drying kinetics of cocoyam cormels as influenced by slice thickness and pre-drying treatment. White-fleshed (NXs. 001) and pink-fleshed (NXs. 002) cocoyam cormels were used for this study. Drying kinetics of the pre-treated cormels (blanched by soaking in hot water at 100oC for 5 minutes) and fresh cormel slices of 2, 3 and 4 mm thicknesses were examined at 60oC. Drying of the cocoyam slices was predominantly in the falling rate period which indicated that moisture removal occurred mainly by diffusion. Drying of thin pre-treated slices of cocoyam cormels is recommended to obtain the faster moisture removal and subsequently, a reduction in the drying period.