Cereal Chem 58:487 - 492.  |  VIEW ARTICLE
Review of Factors Influencing the Dielectric Properties of Cereal Grains.

S. O. Nelson. Copyright 1981 by the American Association of Cereal Chemists, Inc. 

The influence of various factors such as frequency, moisture content, grain density, temperature, chemical composition, and sorption-desorption cycles on the dielectric properties of grain are discussed, based on information in the literature. Frequency and moisture content are the two most important factors. Bulk density and temperature also influence the values of the dielectric properties. The dielectric constant decreases with increasing frequency and decreasing moisture content. It exhibits positive bulk-density and temperature coefficients, whereas the loss tangent and the dielectric loss factor have positive density coefficients but may have positive or negative temperature coefficients, depending upon frequency, moisture-content, and temperature ranges. Dielectric properties of wheat and corn are presented as contour plots for the dielectric constant and the dielectric loss factor as functions of moisture content and frequency. Equations expressing the dielectric constant of shelled, yellow-dent field corn as a function of frequency, moisture content, bulk density, and temperature are also given. Sources of information on dielectric properties of cereal grains are identified in a table indicating ranges of moisture content, frequency, and temperature for which information is available.