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Moisture Limits for Measurement of Moisture in Cereal Grains and Oilseeds Below Zero Degrees Celsius by the Dielectric Method
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: Paper number 033020, 2003 ASAE Annual Meeting . (doi: 10.13031/2013.15399)
Authors: Péter Mészáros, David B. Funk
Keywords: grain moisture, temperature correction, frozen grain, dielectric
Temperature profoundly affects the dielectric constant of moist materials--especially at the
freezing point of water. For liquid water and moist materials that do not involve strong hydrogen
bonding between water and the matrix, a dramatic discontinuity is observed in the dielectric constant
versus temperature curve at zero degrees Celsius. Moisture measurements based on the radiofrequency
dielectric method are essentially blind to "frozen" water. However, in materials such as
grain where a significant fraction of the water is relatively tightly bound to polar molecules, this
discontinuity is absent. The absence of that discontinuity in the dielectric characteristics of dry to
moderately moist grains may permit accurate moisture measurements at temperatures well below
the freezing point of water.