The formation of ice crystals could reduce the
mobility of water molecules in the frozen material and thereby
may affect dipole rotation during the microwave heating. In order
to determine the effect of a pretreatment before microwave drying
on heat generation, the dielectric properties of pretreated samples,
including the dielectric constant (representing the capability to absorb
microwave energy) and the loss factor (representing the capability
to convert absorbed energy into heat) should be taken into
account (Lidstrom et al., 2001).