Performance comparison of RF impedance and DC conductance measurements for single-kernel moisture determination in corn
1991
Nelson, S.O. | Lawrence, K.C. | Kandala, C.V.K.
Two electrical measurement techniques for rapidly determining the moisture content of individual kernels of corn, Zea mays L., were compared directly with an oven drying reference method. One was a dc conductance measurement on kernels as they passed between crushing-roller electrodes. The other involved a radio-frequency (RF) complex impedance measurement on a parallel-plate capacitor with the kernel between the plates. Twenty-kernel samples from bands around the corn ear, near the butt, midsection, and tip, were measured from ears of several moisture levels ranging between 12 and 40%, wet basis, for four yellow-dent field corn hybrids that dried naturally in the fields in Illinois and Nebraska. Both techniques provided reliable kernel moisture contents, independent of kernel size, with standard errors of performance of 0.6 and 0.7% moisture content for the crushing-roller conductance and parallel-plate impedance methods, respectively, and can therefore be recommended for practical application.
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