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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Sensing Methods & Instrumentation for Rapid Determination of Moisture Content... and Other Quality Attributes of Grains, Seeds, & Nuts

Location: Quality and Safety Assessment Research Unit

Project Number: 6612-44000-028-00
Project Type: Appropriated

Start Date: Oct 26, 2010
End Date: Oct 25, 2015

Objective:
1. Develop cost-effective systems and sensors for rapid and nondestructive measurement of moisture content and density of cereal grains, oilseeds and nuts that can be used in static and dynamic situations (on line and in process applications). 2. Develop a portable system for moisture measurements of shelled and unshelled peanuts that can be used in the field and at peanut grading stations. 3. Improve peanut grading processes by developing a rapid system for nondestructive determination of peanut kernel moisture from measurements on pre-cleaned samples and samples consisting of a mixture of pods and foreign materials. 4. Develop methods for monitoring water migration in almonds and other nuts and its effect on their quality by dielectric and spectroscopic methods.

Approach:
Developing a cost-effective microwave system for rapid moisture measurement will require analysis of existing dielectric properties data to determine the optimum frequency and measurement parameters. From these results, microwave components will be specified, assembled into a low-cost rapid prototype, compared to a network analyzer, then calibrated and validated for moisture content of wheat, corn, soybeans, almonds, oats, sorghum, and barley. For peanuts, dielectric properties from 2 to 18 GHz on Runner, Spanish, Valencia, and Virginia will first be collected on shelled and unshelled peanuts. As with the other grains above, these data will then be analyzed to determine the optimum dielectric properties parameters and associated algorithms for a density- and variety-independent measure of peanut moisture content, and a prototype low-cost rapid peanut moisture measurement system will be developed. From these measurements and system development for peanut moisture content of shelled and unshelled peanuts, further development of a system to measure the moisture content of peanut kernels without shelling will be developed. Additional dielectric properties of both the unshelled and shelled kernels will be collected as needed, along with the moisture content of both the shells and the kernels. From these data, moisture algorithms will be developed. Additional dielectric properties measurements on unshelled peanuts with and without foreign material will also be collected for development of moisture models that are also independent of foreign material (trash). Models will be developed for both pod and kernel moisture contents. Besides kernel moisture content, meat content and percentage of foreign material are also important grading parameters. Attempts to correlate the dielectric properties data with these parameters will also be made. For almonds, since no dielectric properties data exists, fundamental dielectric properties measurements of almonds of varying varieties, growing locations in California, and moisture contents will be collected with a network analyzer. Correlations between moisture content and dielectric properties data will be developed. To investigate the dynamics of water migration in the almond kernels, known amounts of water will be sprayed on almond kernels of known moisture content, mixed, and then sealed in a Styrofoam box. The sealed box will then be placed between two horn-lens antennas for free-space measurement of the dielectric properties between 2 and 18 GHz at room temperature. Changes in the dielectric properties will be recorded over time as water moves from the almond surface to water in equilibrium inside the kernels. The next stage will be the use of these dielectric spectroscopic methods to monitor water migration inside the almonds under controlled conditions of humidity and temperature. In this instance, the water will permeate the almonds from the atmosphere for varying relative humidities from 20 to 80% in a controlled environmental chamber. Additionally, measurements will be repeated over varying temperatures from 0 to 50 oC in 5 oC increments.

Last Modified: 7/22/2014
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