Location: Peanut Research
Title: A Low-Cost Impedance Meter for Sensing the Moisture Content of in-Shell Peanuts Authors
Submitted to: IEEE Instrumentation & Measurement Society
Publication Type: Abstract Only
Publication Acceptance Date: December 5, 2009
Publication Date: N/A
Interpretive Summary: None required.
Technical Abstract: A low cost impedance meter developed at the National Peanut Research Laboratory described here was used to generate RF signals at frequencies of 1, 5 and 9 MHz. The RF signals were applied to a parallel-plate capacitor holding a sample of peanuts and the capacitance (C), phase angle (') and impedance (Z) of the system were measured. The measurements were made on in-shell peanuts at eight different moisture levels ranging from 7% to 26% and at ten temperatures from 0oC to 45oC at intervals of 5oC. A calibration model was developed using the measured values of C, ' and Z at different temperatures on samples of known moisture contents as determined by the standard air-oven method. Temperature correction was included in the model development to felicitate the use of the impedance meter in field conditions, where the temperature variations could affect the accuracy of moisture readings. Multi linear regression analysis was done with full cross validation to develop the model. Moisture contents predicted by this method were compared with their standard air-oven values for validation. This method being nondestructive and rapid will have considerable application in the sale and purchase, and drying and storage processes of peanuts.