COMPARISON OF DC CONDUCTANCE, RF IMPEDANCE, MICROWAVE, AND NMR METHODS FOR SINGLE-KERNEL MOISTURE MEASUREMENT IN CORN

ABSTRACT Methods for rapidly measuring the moisture content of individual com, Zea mays L., kernels are discussed. Direct comparisons of kemel moisture content determinations by single-kernel oven drying, nuclear magnetic resonance (NMR) measurements, parallel-plate radio-frequency (RF) complex impedance measurements, and crushing-roller dc conductance measurements are presented. These single-kemel moisture content values are compared to standard oven drying and Karl Fischer moisture content determinations on bulk grain samples from the same com lots equilibrated at moisture contents between 10 and 40%, wet basis. Comparisons of the RF complex impedance and crushing-roller dc conductance determinations of single-kemel moisture measurements on com and similar data for microwave resonant cavity perturbation measurements for the same purpose are discussed. All four electrical methods can provide single kemel com moisture measurements with standard errors of performance of less than 1% moisture content, which should be suitable for practical use. Aspects of the development of suitable equipment to use these principles in practical applications are also discussed.