Capacitance Sensor for Nondestructive Measurement of Moisture Content in Nuts and Grain

Abstract

This paper presents a portable electrical instrument that measures the complex impedance of a parallel-plate capacitor with a sample of peanut kernels between its plates. A novel method of measuring the capacitance and phase angle of a parallel-plate system is described. The measured values were used in an empirical equation to estimate the moisture content (mc) of the sample. The estimated values were in good agreement with the mc values that are obtained by a standard air-oven method. This method can be used to estimate the mc in other types of nuts and grain by calibrating the instrument with samples of these materials with known mc values. This instrument would be useful in grain industries for quick and nondestructive mc measurement.