2 indicate that the drying
rates of red bell-pepper in open sun drying and microwave
oven drying at 700Wwere faster than the other methods and
parameters applied. During drying all the free water is evaporated
and the evaporation front moves into the interior of the
product. When this occurs, (moisture) mass transfer is then
by molecular (liquid) diffusion or vapor diffusion or by capillary
forces in the wet (i.e. interior) regions to the surface of the
product where evaporation occurs. This diffusion process of
water through the dry outer layers to the surface is influenced
by high temperatures (Karathanos and Belessiotis, 1997). As a
result, the diffusion process was faster during the drying of
bell-pepper in a microwave oven (700W) than in oven drying
because of the higher drying air temperature. In the case of sun
drying the faster drying rate might be due to air flowas the drying
took place under direct sunlight which the materials were
exposed to wind flow