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Submitted to: Journal of Food Measurement and Characterization
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/4/2017 Publication Date: 5/5/2018 Citation: Trabelsi, S. 2018. Measuring changes of radio-frequency dielectric properties of chicken meat during storage. Journal of Food Measurement and Characterization. 12(2):683-690. Interpretive Summary: Chicken meat freshness and other quality-related attributes are of interest to both producers and consumers. Currently, these attributes are assessed through measurement of several physical properties including color, pH, water holding capacity, drip loss, cook yield and texture. Procedures for determining these factors are tedious, time consuming, and involve various types of costly instrumentation. Therefore, there is a real need for methods and sensors for rapid assessment of the freshness and other quality-related attributes of chicken meat. Radio-frequency dielectric spectroscopy may have the potential to form the foundation for development of such methods and sensors. However, some challenges must be overcome before this can be achieved. A major challenge is how to correlate measured dielectric properties, which are intrinsic properties of the material, with quality attributes which are mostly empirical and subjective. Therefore, effects of chicken meat aging on its quality attributes were investigated through measurement of the dielectric properties at radio-frequencies between 200 MHz and 20 GHz. Results show decrease of the dielectric constant with the storage duration at all frequencies while the dielectric loss factor increased with storage duration at frequencies below 3.0 GHz and decreased slightly or remained constant at frequencies above that. Data analyzed at 500 MHz show that the dielectric loss factor and loss tangent increased nearly linearly with the storage duration. Similarly, the loss tangent increased with water loss. This indicates that the dielectric properties can be used for rapid and nondestructive assessment of the freshness of chicken meat, but further research will be needed to develop practically useful techniques of benefit to producers and consumers. Technical Abstract: Changes in dielectric properties of stored chicken meat were tracked by using a radio-frequency dielectric spectroscopy method. For this purpose, the dielectric properties were measured with an open-ended coaxial-line probe and vector network analyzer over a broad frequency range from 200 MHz to 20 GHz at 23 oC. Chicken meat samples were stored in a refrigerator for 8 days at 4 oC. Dielectric constant and loss factor were measured daily over that period. The dielectric constant decreased with frequency and storage duration with a slope change at about 4 GHz. The dielectric loss factor increased with storage duration for frequencies below 3 GHz and remained almost constant above that. The frequency dependence of the dielectric loss factor was dominated by ionic conduction in the lower frequency range and dipolar relaxation of water above 3 GHz. For frequencies below 3 GHz, both the dielectric loss factor and loss tangent increased linearly with storage duration. A three-dimensional representation of the dielectric loss factor as a function of storage duration and conductivity provided analytical expressions that can be used to track chicken meat aging from measurement of the dielectric properties at a single frequency. |
