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Author(s)

First Name / Middle Name / Surname / Role / Email
Stuart / O. / Nelson / Life Fellow /
Organization / Address / Country
USDA, ARS / P. O. Box 5677, Athens, GA / USA
First Name / Middle Name / Surname / Role / Email
Samir / Trabelsi / Member Engineer /
Organization / Address / Country
USDA, ARS / P. O. Box 5677, Athens, GA / USA
First Name / Middle Name / Surname / Role / Email
Hong / Zhuang / r
Organization / Address / Country
USDA, ARS / P. O. Box 5677, Athens, GA / USA

Publication Information

Pub ID / Pub Date
073095 / 2007 ASABE Annual Meeting Paper

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An ASABE Meeting Presentation

Paper Number: 073095

Dielectric Spectroscopy of Fresh Chicken Breast Meat

Stuart O. Nelson, Samir Trabelsi, and Hong Zhuang

U. S. Department of Agriculture, Agricultural Research Service, RichardB.RussellAgriculturalResearchCenter, P. O. Box 5677, Athens, Georgia 30605-5677

Written for presentation at the

2007 ASABE Annual International Meeting

Sponsored by ASABE

MinneapolisConvention Center

Minneapolis, Minnesota

17 - 20 June 2007

Abstract.The dielectric properties of fresh chicken breast meat were measured at temperatures from 5 to 85 C over the frequency range from 10 MHz to 1.8 GHz by dielectric spectroscopy techniques with an open-ended coaxial-line probe and impedance analyzer. Samples were cut from both the Pectoralis major and Pectoralis minor muscle tissue for the measurements and placed in a temperature-controlled sample holder for the dielectric spectroscopy measurements. Samples representing two time periods after deboning, 2 h and 24 h postmortem, were included in the study. For the temperature range from 5 to 65 C, temperature dependence and frequency dependence of the dielectric constant were similar for both kinds of muscle tissue and for the two deboning times. The temperature coefficient for the dielectric constant was positive at frequencies below about 200 MHz and negative at frequencies above that region. The dielectric loss factors were also similar in their frequency and temperature dependence for both kinds of muscle tissue and both deboning times. The behavior of the dielectric properties at temperatures above 65 C was less predictable, probably because of changes due to cooking of the tissue. In general, dielectric properties of P. minor were somewhat greater than those of P. major, but values for the two deboning times were similar.

Keywords.Dielectric spectroscopy, chicken meat, deboning time, Pectoralis, dielectric constant, dielectric loss factor, dielectric properties, permittivity

Introduction

Dielectric properties of materials are those electrical characteristics of materials that influence the interaction of the materials with electric fields. They are important in radio-frequency and microwave dielectric heating applications, because the dielectric properties of the materials subjected to the electromagnetic fields determine the field distribution and the energy absorbed from those fields (Nelson, 1991; Nelson, 2006). Thus, dielectric properties are important in such applications as microwave heating of foods (Nelson and Datta, 2001). They are also important in applications such as the sensing of moisture content in grain and seed, which is possible because of high correlations between dielectric properties of these materials and their moisture content (Nelson, 1991; Nelson and Trabelsi, 2004). Dielectric properties have also been considered for other quality sensing possibilities (Nelson et al., 2006)

Dielectric spectroscopy implies the study or measurement of dielectric properties of materials across broad ranges of frequency, and a number of agricultural applications have been considered (Nelson, 2004; Nelson, 2005). Dielectric properties have been defined and those properties of agricultural materials discussed in some detail (Nelson, 1973). However, the dielectric properties of interest here are the dielectric constant and dielectric loss factor, the real and imaginary parts, respectively, of the complex permittivity relative to free space,. The dielectric constant is associated with the capability for energy storage in the electric field in a material. It also influences the amount of electromagnetic energy reflected from a product or transmitted into the product. The dielectric loss factor describes how well a material absorbs energy from electric fields and converts that energy to heat. Both properties are affected by the frequency of the electromagnetic fields, temperature, material density, and composition, particularly the amount of water present.

Dielectric properties have been considered for quality determination in fish and meat. An electronic fish freshness meter was developed that used the response of a 2-kHz circuit to changes in the dielectric properties as the fish aged (Jason and Richards, 1975). Kent studied and reported extensively on the low-frequency and microwave dielectric properties of fish for quality sensing (Kent, 1983; Kent et al., 2004). The dielectric properties have also been studied for use in detection of added water in chicken breast meat (Kent and Anderson, 1996) and in pork products (Kent et al., 2002). Dielectric properties of pork have also been used in detection of pale soft exudative meat (Pfuetzner et al., 1985).

With respect to poultry, dielectric properties data have been more limited. Dielectric properties of raw chicken were measured over the 100- to 2500- MHz frequency range at temperatures of 1, 25, and 40 C (Tran and Stuchly, 1987). Dielectric properties from 200 MHz to 12 GHz at about 0 C were also reported for unprocessed chicken breast meat (Kent and Anderson, 1996), and data have been reported for raw and processed turkey meat at 915 and 2,450 MHz (Sipahioglu et al., 2003).

The objective of this study was to determine dielectric properties of fresh chicken breast muscle at frequencies from 10 to 1800 MHz at temperatures from 5 to 85 oC and to study the effect of postmortem ageing time and chicken breast muscle types on the measured dielectric properties.

Materials and Methods

Chicken Samples

Fresh chicken carcasses of about 1.5-kg weight were obtained from a local processing plant, placed in a cooler and transported to the laboratory with carcass temperature of 3 to 4oCon arrival. Muscles from the right breast half were removed from carcasses at the 2-h postmortemstage, whereas the other breast half was left on the carcass with normal attachment to the skeletal restraints intact. Both the removed half breast and the carcass with the left half breast weresealed in plastic bags andstored at 2oC. At 24-h postmortem, the left half breast was also removed from the carcass, and dielectric properties measurements were then taken on both the 2-h and 24-h deboned samples. Samples for moisture determination were taken when the half breasts were separated into Pectoralis major and Pectoralis minor muscles, and moisture contents of each for each half breast were determined by AOAC methods (AOAC, 1990). The entire study was replicated 4 times and completed in 5 weeks.

Dielectric Properties Measurements

The electrical measurements necessary for dielectric properties determination were obtained with a HewlettPackard[1]85070B openended coaxialline probe, a HewlettPackard 4291A Impedance/Material Analyzer, and a temperaturecontrolled stainless steel sample cup and water jacket assembly designed and built for use with the 85070B probe (Nelson, 2003). Dielectric properties (dielectric constant and loss factor) were calculated with Agilent Technologies 85070D Dielectric Probe Kit Software, modified for use with the HP 4291A Analyzer by Innovative Measurement Solutions, which provided dielectric properties values from the reflection coefficient of the material in contact with the active tip of the probe(Blackham and Pollard, 1997). Settings were made to provide measurements at 51 frequencies on a logarithmic scale from 10 MHz to 1.8 GHz. The 4291A Analyzer was calibrated with an open, short, and matched load prior to the calibration of the open-ended coaxial-line probe with measurements on air, a short-circuit block, and glass-distilled water at 25C. A personal computer was used to control the system and record resulting data (Nelson, 2003).

Measurement Procedures

Chicken breast musclesamples were cut with a 21-mm cork borer with its axis perpendicular to the muscle fiber direction. A razor blade was used to cut the cylindrical samples to lengths of about 1cm and provide a smooth plane surface for the measurement. Samples weighed about 3.3g. The sample was inserted into the sample cup with the skin side of the meat samples facing the probe, and the muscle fiber direction of the sample was perpendicular to the axis of the probe. The sample cup and water jacket assembly was raised to bring the sample into firm contact with the open-ended coaxial-line probe for the permittivity measurements (Nelson, 2003). The sample was allowed to come into temperature equilibrium with the circulating water at 5oC before the first permittivity measurement to be recorded was triggered (the water temperature in the circulator had been lowered to 5oC by the addition of crushed ice). After the initial measurement, permittivity measurements were taken at 10 or 20oC intervals up to 85oC. After the circulator raised the water temperature to the target value, a subsequent period of 3 min. was provided for the sample to equilibrate to the new temperature. The entire measurement sequence was completed in about 60 minutes.

Results and Discussion

Average moisture contents of both P. major and P. minor muscle tissues were 76%, wet basis, for both 2-h and 24-h postmortem deboning. The dielectric properties of the chicken breast meat deboned at 2 h postmortem are presented for the P. major and P. minor muscles in figures 1 and 2, respectively, for temperatures from 5 to 65 C over the frequency range from 10 MHz to1.8 GHz. Dielectric properties at temperatures above 65 C were less predictable, probably because of tissue changes due to cooking and are not presented here. Dielectric constant values for P. minor are somewhat greater than those of P. major at all temperatures. The loss factor values for the two muscle types, however, are very nearly the same.

For the meat deboned at 24 h postmortem, the dielectric properties for the same range of temperature and frequency are shown in figures 3 and 4. In these tissues, the dielectric constants of P. minor muscle are also larger than those of P. major. The loss factors for the 24-h deboned tissue are also consistently lower than those of the 2-h deboned tissue.

Figure 1. Frequency and temperature dependence of the dielectric properties of fresh chicken breast meat, P. major, deboned at 2 h postmortem. / Figure 2. Frequency and temperature dependence of the dielectric properties of fresh chicken breast meat, P. minor, deboned at 2 h postmortem.
Figure 3. Frequency and temperature dependence of the dielectric properties of fresh chicken breast meat, P. major, deboned at 24 h postmortem. / Figure 4. Frequency and temperature dependence of the dielectric properties of fresh chicken breast meat, P. minor, deboned at 24 h postmortem.
Figure 5. Log-log plots of the dielectric loss factor vs. frequency for 2-h deboned chicken breast meat showing linear relationships.

At frequencies below about 200 MHz, the dielectric constant increases with increasing temperature, whereas it decreases with increasing temperature at frequencies above that region. This behavior at lower frequencies is consistent with the dominance of ionic conduction and is characteristic of dipolar rotation at the higher frequencies.

Log-log plots of the dielectric loss factor vs. frequency are shown in figure 5 for the two muscle types deboned at 2 h postmortem. They illustrate the linear relationship characteristic of ionic conduction in materials.

Values for the dielectric constants and loss factors of the chicken breast meat are shown for 26 MHz and 1.8 GHz in Tables 1 and 2. Data for these frequencies were selected since they are near each end of the frequency range measured and are close to the ISM (Instrumentation, Scientific, and Medical) frequencies allocated for dielectric heating at 27 MHz and microwave heating at 915 MHz and 2.45 GHz. The positive and negative temperature coefficients of the dielectric constants at the lower and higher frequencies are illustrated in the tabular data as well as the magnitude comparisons for the two muscle types and the deboning periods. Similar comparisons can be noted for the dielectric loss factor, except that the temperature coefficient is positive at both frequencies.

These results suggest that it may be possible to use dielectric properties measurements to assess differences in chicken meat muscle types, deboning time and related quality.

Table 1. Dielectric constants of fresh chicken breast meat at indicated temperatures, frequencies, and periods after removal from the carcass.

Temp.,
C / Deboned 2 h postmortem / Deboned 24 h postmortem
26 MHz / 1.8 GHz / 26 MHz / 1.8 GHz
P. major / P. minor / P. major / P. minor / P. major / P. minor / P. Major / P. minor
5 / 92 / 96 / 56 / 58 / 92 / 93 / 56 / 56
25 / 100 / 103 / 56 / 57 / 100 / 102 / 56 / 56
45 / 108 / 112 / 55 / 56 / 109 / 114 / 53 / 56
65 / 127 / 129 / 53 / 54 / 129 / 136 / 49 / 54

Table 2. Dielectric loss factors of fresh chicken breast meat at indicated temperatures, frequencies, and periods after removal from the carcass.

Temp.,
C / Deboned 2 h postmortem / Deboned 24 h postmortem
26 MHz / 1.8 GHz / 26 MHz / 1.8 GHz
P. major / P. minor / P. major / P. minor / P. major / P. minor / P. Major / P. minor
5 / 362 / 377 / 18.0 / 18.8 / 342 / 361 / 17.8 / 18.1
25 / 527 / 550 / 18.4 / 18.9 / 510 / 535 / 18.1 / 18.4
45 / 735 / 754 / 20.2 / 20.7 / 708 / 751 / 20.0 / 20.5
65 / 943 / 979 / 23.2 / 23.8 / 896 / 964 / 22.7 / 23.6

Conclusion

The dielectric constants and loss factors of uncooked chicken breast muscle, P. minor and P. major,deboned at 2 h and 24 h postmortem, decrease with increasing frequency from 10 MHz to 1.8 GHz at temperatures in the range from 5 to 65 C. Dielectric constants of P. minor muscle tissue, deboned at both 2 h and 24 h postmortem, are somewhat greater than those for P. major muscles at all frequencies and temperatures. Dielectric loss factors of both muscle types deboned at 2 h are very nearly the same. For the 24-h deboning, dielectric loss factors for P. minor muscle tissue had somewhat higher dielectric loss factors than the 2-h deboned muscle tissue.

At frequencies below about 200 MHz, the dielectric constant of the chicken breast tissue has a positive temperature coefficient, and above that frequency region the temperature coefficient is negative, following the expected behavior in frequency ranges where ionic conduction or dipolar losses are the dominant loss mechanisms.

References

AOAC. 1990. Official Methods of Analysis, 15th edition. Association of Official Analytical Chemists, Washington, DC.

Blackham, D. V. and R. D. Pollard. 1997. An improved technique for permittivity measurements using a coaxial probe. IEEE Transactions on Instrumentation and Measurement 46(5): 1093-1099.

Jason, A. C. and J. C. S. Richards. 1975. The development of an electronic fish freshness meter. Journal of Physics E: Scientific Instruments 8: 826-830.

Kent, M. 1983. The effects of spoilage on the dielectric properties of frozen fish. Journal of Science in Food and Agriculture 34: 1289-1296.

Kent, M. and D. Anderson. 1996. Dielectric studies of added water in poultry meat and scallops. Journal of Food Engineering 28: 239-259.

Kent, M., J. Oehlenschlagelr, S. Mierke-Klemeyer, R. Knoschel, F. Daschner and O. Schimmer. 2004. Estimation of the quality of frozen cod using a new instrumental method. European Food Research and Technology 219: 540-544.

Kent, M., A. Peyman, C. Gabriel and A. Knight. 2002. Determination of added water in pork products using microwave dielectric spectroscopy. Food Control 13: 143-149.

Nelson, S. O. 1973. Electrical properties of agricultural products -- A critical review. Transactions of the ASAE 16(2): 384-400.