Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2009.3116.3120HiiC.L. LawC.L. ClokeM. 122009917Effective diffusivity is an overall mass transport property of water which includes liquid diffusion, vapour diffusion, hydrodynamic flow and other possible mass transfer mechanisms. These mechanisms control the moisture migration process in material during drying. The objective of this study is to determine the effective diffusivities of cocoa beans using a variable diffusivity model based on Fick’s second law of diffusion. Experiments were conducted using forced air at temperatures of 39.3 and 53.3°C. Three empirical models were used namely the linear, quadratic and exponential types. Modeling was carried out using the explicit finite difference method based on drying kinetics. The goodness of fit was compared using the mean relative error (E%) between the experimental and predicted data. Mean relative error was the lowest using the quadratic empirical model (E (%) = 3.01-4.93) as compared to the linear (E (%) = 8.16-11.11) and exponential (E (%) = 3.91-7.47) models. The effective diffusivity values are in the order of 10^{-10} to 10^{-11} which is within the range as those reported in literatures.]]>Karathanos, V.T., G. Villalobos and G.D. Saravacos,1990Crank, J.,1975Luangmalawat, P., S. Prachayawarakorn, A. Nathakaranakule and S. Soponronnarit,2008Tuwapanichayanan, R., S. Prachayawarakorn and S. Soponronnarit,2008Chemkhi, S. and F. Zagrouba,2005Zogzas, N.P., Z.B. Maroulis and D. Marinos-Kouris,1996Shi, J., Z. Pan, T.H. McHugh, D. Wood, E. Hirschberg and D.A. Olson,2008