Single-kernel moisture determination in peanuts by complex RF impedance measurement.

ABSTRACT A technique is described for rapidly and nondestructively determining the moisture content of individual peanut, Arachis hypogaea L., kernels. This technique requires the measurement of the complex impedance of a parallel-plate capacitor with the kernel held between the plates. Moisture content is reliably determined, independent of peanut size variation, from data obtained by measuring the difference in capacitance and dissipation factor, and/or phase angle at two frequencies, 1.0 and 4.5 MHz. Standard error of performance, as compared to a standard oven method for moisture determination, was about 0.5% moisture content or less on peanut samples of moisture contents between 5 and 15% Trom both 1988 and 1989 crops.