Dielectric Properties of Importance in Operations of Post-harvest of Sorghum

The knowledge of electrical properties and their relationship with moisture content is of great importance in operations of post-harvest and storage in grains. The dielectric properties of sorghum samples were studied at different moisture contents and temperatures (25 at 41 C-omicron), at frequencies of 1 and 10 kHz. In order to measure changes in the capacitance and dissipation factor of the samples, the method of impedance bridge was used. Both the dielectric constant and the dielectric loss factor of the samples increased with increasing moisture content and temperature; however, they decreased with increasing frequency. Models were proposed to relate the dielectric properties to either the moisture (exponential and polynomial) or temperature (linear).