3.3. Dielectric properties during FD
From Figs. 7 and 8 the measured values of e0 and e00 of the drying
samples were found to increase to a maximum value and then decrease
with drying time, while the moisture content decreased
gradually with sublimation of the ice crystals in a logarithmic form.
In the initial stage of FD and up to 2 h, the temperature in the center
of the samples rises and ice crystals start to sublime leading to
gradual increase of dried layers in samples. In this stage both e0 and
e00 values consist of dried region and frozen region which did not
sublime in the samples. The reason that both e0 and e00 values rose
as drying continued might be due to large amount of unfrozen
water (un-freezable and bound water) present in the frozen regions
resulting in the higher e0 and e00 values (Figs. 5 and 6) than