Determining Moisture Content in Small Wheat Samples by Dual-frequency R F Impedance Sensing

A technique is described for estimating moisture content of small samples of hard red winter wheat (10 to 30 kernels) by impedance measurements at 1 and 4.5 MHz on a parallel-plate capacitor holding the sample between the plates. The measurement system was calibrated by measurements on samples, ranging from 9 to 20% moisture content, wet basis, from three wheat cultivars grown in 1991 and 1992, Validation measurements were taken for prediction of moisture content of small wheat samples from three different cultivars harvested in 1992, Moisture contents of the small samples were predicted with a five-variable equation involving differences in the real and imaginary components of the complex impedance at the two frequencies. The standard error was 0,9% moisture content. The study established a basis for farther development of the rapid, nondestructive method for estimating moisture content of small wheat samples.