Nondestructive method to estimate moisture content in single nuts and grain from RF Impedance measurements with a parallel-plate sensor

摘要

A method to determine the moisture content from the complex impedance measurements of a parallel-plate capacitor with a single shelled or in-shell peanut between the plates, at two frequencies 1 and 5 MHz, is described here. Capacitance (C), phase angle (θ) and dissipation factor (D) of the parallel-plate system at the two frequencies were measured. Using these values in a derived empirical equation, the moisture content (mc) of the peanuts was estimated to an accuracy of within 1% of the standard air-oven value. The moisture range of the peanuts tested was between 5 and 20%. The method is rapid and nondestructive and was found earlier to be applicable in certain types of grain such as corn. The study establishes a basis for the development of a practical instrument that could be useful in the grain and peanut industry.