In general, drying of foods takes place in two
periods, a constant rate and a falling rate period. The
mode of moisture movement within a hygroscopic
solid during the falling rate period could be represented
by effective moisture diffusion phenomenon and
represents an overall mass transport property of water
in the material. During drying it can be assumed that
diffusivity explained with Fick’s diffusion equation is
the only physical mechanism to transfer the water to
surface (Dadali et al., 2007; Dincer and Dost, 1995;
Wang et al., 2007). Effective moisture diffusivity
which is affected by composition, moisture content,
temperature and porosity of the material, is used
due to the limited information on the mechanism of
moisture movement during drying and complexity of
the process (Abe and Afzal, 1997). For the solution
of Fick’s diffusion equation, the Pandanus leave
pieces were assumed as a slab. The effective moisture
diffusivity was calculated by using the following
equation (Crank, 1975)