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United States Department of Agriculture

Agricultural Research Service

Title: Capacitance Sensor for Nondestructive Meaurement of Moisture Content in Nuts and Grain

Authors
item Kandala, Chari
item Nelson, Stuart

Submitted to: Institute of Electrical and Electronics Engineers
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2005
Publication Date: June 1, 2005
Citation: Kandala, C., Nelson, S.O. 2005. Capacitance sensor for nondestructive meaurement of moisture content in nuts and grain. Institute of Electrical and Electronics Engineers.

Interpretive Summary: none required.

Technical Abstract: A method was developed earlier for estimating the moisture content in samples of wheat, corn and peanut kernels, nondestructively, by measuring their complex impedance values. In this method, capacitance, phase angle and dissipation factor were measured with an impedance analyzer at 1 and 5 MHz on a parallel-plate capacitor holding a few kernels of a particular commodity between the plates. These values were then used in an empirical equation and the moisture contents were calculated successfully within 1% of their air-oven values for about 85% of the kernel samples tested in the moisture range of 6 to 20% for wheat, corn and peanuts. However, it would be useful during drying and processing if the moisture content could be determined, for commodities such as peanuts, without shelling them. In this work, the feasibility of determining the moisture content of in-shell peanuts (pods) by similar impedance measurements was investigated. Measured values of capacitance, phase angle and dissipation factor were used in a modified prediction equation and the moisture contents were estimated within 1% of their air-oven values, for over 80% of the pod samples tested, in the moisture range of 7 to 20%. The method is rapid and nondestructive and may be used in the development of a commercial instrument.

Last Modified: 10/23/2014
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