Although high moisture
foods like mushrooms can be expected to have a constant
rate of drying, this was not observed in the present study,
may be because of the thin (single) layer arrangement and
too rapid heating by microwaves, providing instant drying.
As expected, higher drying rates were obtained with
higher microwave power. It can be seen from the figure
that the influence of power on drying rate is markedly
higher when the moisture is higher. At moisture content
of less than 4.0 kg/kg d.b. there is no difference in the drying
rates among different power levels, indicating the significance
of internal resistance to mass transfer at low
water content in the material. The amount of microwave
energy absorbed by the material depends upon its dielectric
properties and the electric field strength