Study on Rapid Measurement of Soybeans Moisture Content Based on Dielectric Properties

For the purpose of rapid and nondestructive determination of soybean moisture content, a new measurement principle based on the dielectric properties of the measured plant material was proposed and a moisture measuring device making use of this principle was designed. The device was comprised of a sleeve capacitance in which the soybeans to be measured was packed, a signal generator and a signal measuring instrument. The relationships between relevant dielectric parameters (equivalent capacitance, resistance and loss tangent) and moisture content of soybeans in the capacitance cylinder under different excitation frequency were examined. In the tests performed in our laboratory, the optimal frequency was found to be about 1 kHz, at which the capacitance in relation to moisture content can be represented by a power function. The errors involved in this new method were analyzed