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Observations on rheological, electrical, and optical changes during rigor development in pork and beef
1Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
Journal of Animal Science
|April 1, 1997
Summary
Electrical and optical properties change during meat rigor development. Consistent predictors include capacitance at 120 Hz and resistance at 10 kHz, though complex changes hinder early meat quality prediction.
Area of Science:
- Meat science
- Biophysics
- Food technology
Background:
- Postmortem muscle changes, known as rigor development, significantly impact meat quality.
- Understanding these changes is crucial for predicting meat characteristics like tenderness and pH-dependent qualities.
Purpose of the Study:
- To investigate electrical and optical property changes during postmortem rigor development in bovine and porcine muscle.
- To identify reliable electrical and optical predictors for rigor progression and assess their potential for early meat quality assessment.
Main Methods:
- Sinusoidal testing of bovine sternomandibularis and porcine sternocephalicus muscle strips in a rigorometer up to 3 hours postmortem.
- Measurement of electrical impedance (capacitance and resistance) at various frequencies (120 Hz, 1 kHz, 10 kHz) and fiber-optic reflectance.
- Analysis of mechanical properties including muscle elongation, stress-strain hysteresis, and elastic modulus, considering loading rate effects.
Main Results:
- Rigor development correlated with decreased muscle elongation, reduced stress-strain hysteresis, and increased elastic modulus, which was influenced by loading rate.
- Electrical impedance showed changes: capacitance decreased and resistance increased at 120 Hz, 1 kHz, and 10 kHz, with capacitance at 120 Hz and resistance at 10 kHz being the most consistent predictors.
- Fiber-optic reflectance showed increases near 400 nm and decreases near 700 nm, generally occurring later than electrical changes. Dimensional effects from stretching could introduce errors in electrical impedance measurements.
Conclusions:
- Electrical and optical measurements reflect rigor development in muscle, with specific frequencies showing consistent changes.
- While electrical and optical properties change, their complex and sometimes asynchronous nature presents challenges for the early prediction of pH-dependent meat quality attributes.