all the microwave energy is mainly absorbed by water for heating and vaporization, and only a fraction is absorbed by the essential oils inside the sample. Another explanation for the effect of the initial moisture content observed in the diffusion rates, that can be associated with the presence of
higher porosity in the bed of dry samples than in the bed of wet samples,
which also promotes the contact of the solvent with the particle surface (Eggers and Pliz, 2011).