Rapid Sensing of Peanut Kernel Moisture Content from Microwave Permittivity Measurements on Unshelled Pods

Authors: Trabelsi, Samir; Lewis, Micah; Nelson, Stuart

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2009
Publication Date: 6/1/2009
Citation: Proceedings of the 8th Intrnational Conference on Electromagnetic Wave Interaction with Water and Moist Substances (ISEMA 2009). Rapid Sensing of Peanut Kernal Moisture Content from Microwave Permittivity Measurements on Unshelled Pods. Trabelsi, S., Lewis, M.A., Nelson, S.O. 2009. pp. 405-407.

Interpretive Summary: Electrical permittivities, or dielectric properties, of materials are those electrical characteristics that determine how they interact with electromagnetic fields. The dielectric properties of materials such as grain and oilseeds are closely related to the amount of water that they contain. Consequently, instruments can be designed to sense these dielectric properties and be calibrated to read moisture content. Such instruments, called moisture meters, are widely used in the grain and seed trade for rapid determination of moisture content. Moisture content is especially important in the sale and storage of peanuts so that spoilage and development of toxins can be avoided. If kernel moisture contents of peanut lots exceed 10.5 percent, sale is unlawful. Microwave dielectric properties of peanuts are being studied for use in development of microwave moisture meters for use in the peanut industry. In particular, the microwave measurement technique provides a method for reliably measuring the moisture content of the peanut kernels from measurements on the unshelled peanut pods. In these studies moisture content of kernels from such measurements were determined with accuracies of one quarter of one percent moisture content. Current moisture meters require the shelling of samples to determine moisture content of the kernels. At peanut buying points, samples go through a thorough grading process before the moisture content is determined, and at that time the decision is made as to whether the peanut lot can be sold Thus, the new microwave moisture technique offers a real advantage in peanut grading operations, because moisture content can be determined at the beginning of the grading process, and if it is too high, the time and labor lost in grading those samples can be avoided. New microwave moisture meters will therefore be helpful in improving efficiencies of grading and processing as well as preventing losses due to spoilage and will be useful tools for peanut farmers, handlers, and processors, thus providing high quality products for consumers.

Technical Abstract: A method for moisture determination in peanut kernels from measurement of the dielectric properties of peanut pods at microwave frequencies is presented. Results from measurements at 8 GHz show that kernels moisture content can be predicted with a standard error of calibration of 0.25%.