Phase angle and Impedance Measurements for Nondestructive Moisture Content Determination of In- Shell Peanuts Using a Cylindrical Sample Holder

Two parallel-plate electrodes were mounted inside a cylinder, made of a non-conducting material. The space between the plates was filled with peanut pods and the capacitance and phase angle of this system was measured with a prototype low-cost impedance meter, designed for this purpose. Measurements were made at frequencies of 1 and 5 MHz on peanut pod (in-shell) samples of known moisture content between 7 and 17% (wet basis). Using these measured values an empirical equation was developed from which the average moisture content of a peanut pod sample could be calculated from its impedance values. The calculated moisture content values were compared with their air-oven values and were found to be within 1% of the air-oven values for over 95% of the samples tested. The size of the sample used was about 100 g and no shelling or cleaning of the sample was involved. This method is rapid and nondestructive.