Author
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Nelson, Stuart |
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Submitted to: Microwave Power Symposium Proceedings
Publication Type: Proceedings Publication Acceptance Date: 5/13/2005 Publication Date: 7/12/2005 Citation: Nelson, S.O. 2005. Temperature and frequency dependence of the dielectric properties of fresh fruits and vegetables. In: Proceedings of the 39th Annual Microwave Symposium, July 13-16, Seattle, WA. p. 11-14. Interpretive Summary: There is a need for non-subjective determination of product quality in the handling of fresh fruits and vegetables. Ability to rapidly sense quality by use of intrinsic properties of the fruits and vegetables would be very helpful in the sorting and grading of these products for the market. Dielectric properties can be sensed with appropriate instruments that use electric fields for nondestructively probing the products. Radio-frequency dielectric properties of several fresh fruits and vegetable were measured and analyzed to provide background data for further research on this problem, and results of the research are reported in this paper. The variation of the dielectric properties of samples of apple, avocado, banana, cantaloupe, carrot, cucumber, grape, orange, and potato with frequency in the range from 10 to 1,800 MHz and with temperature over the range from 5 to 65 degrees C was determined. The data provide interesting observations on the dielectric behavior of these fresh fruit and vegetable tissues, which determines how the tissues interact with electric fields that can be used to probe the quality of these products. Further studies are needed to learn whether these dielectric properties can be well related to quality factors, such as maturity, moisture content, and dry matter, which are properties of interest in working with many fruits and vegetables. Such future studies will determine whether the principles considered may be adapted to new instruments that can sense quality factors and provide advantages for producers handlers and consumers of these important agricultural products. Technical Abstract: Dielectric properties of tissue from fresh apple, avocado, banana, cantaloupe, carrot, cucumber, grape, orange, and potato were measured with an open-ended coaxial-line probe at frequencies from 10 MHz to 1.8 GHz and at temperatures from 5 to 65 degrees Celsius. Sample results are presented graphically for navel orange and cucumber tissue, and summary data for all nine fruits and vegetables are tabulated at 10 MHz, 100 MHz and 1 GHz at 25 degrees Celsius. |
