Moisture Dependent Diffusion and Shrinkage in Yam during Drying

Abstract

Crank’s analytical approximations for Fick’s diffusion equation were used to investigate the effect of moisture dependent sample thickness and diffusivity on the behavior of yam (Dioscoreaceae rotundata) cubicles during drying processes. Drying and shrinkage experiments were separately conducted at temperatures of 30, 40 and 50 °C in a cabinet drier. The comparative study of moisture dependent shrinkage and moisture dependent diffusivity justifies the interdependence of diffusivity and shrinkage due to water loss during drying. The behavior for yam is best explained by a combination of fractal moisture dependent shrinkage and moisture dependent diffusion, describing both the drying and rate curves better with good prediction of the high moisture regions. This assertion was reached as a result of low mean square error, standard error, percentage relative deviation, Akaike’s Information Criterion and high coefficient of determination. The results may indicate a varying mobility of water in food matrix of different moisture content in the multilayer and monolayer regimes.