Estimating the moisture content of grain from impedance and phase angle measurements

A simple, low cost instrument that measures impedance and phase angle was used along with a parallel-plate capacitance system to estimate the moisture content (MC) of yellow corn. A sample of corn weighing about 100 g was placed between the parallel-plate electrodes and the impedance and phase angle of the system were measured. A semi-empirical equation was developed with the measured values, and their MC values determined earlier by standard air-oven method , using multiple linear regression (MLR) methods. MC values of corn samples in the moisture range of 6% to 20%, not used in the calibration, were predicted by the equation and compared with their standard air-oven values. For over 93% of the samples tested the predicted MC values were within 1% of the air-oven values. This method being nondestructive and rapid will have considerable application in the drying and storage processes of corn and similar grain products.