30C-1 |
Stress relaxation behavior of beef to predict tenderness |
D. PARK1, R. K. Miller1, J. Ophir2, and T. A. Krouskop3. (1) Department of Animal Science, Meat Section, Texas A&M University, College Station, TX 77843-2471, (2) Department of Radiology, University of Texas Health Science Center in Houston, Houston, TX 77030, (3) Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, TX 77030 To understand fundamental rheological properties of beef muscle and its relationship to cooked meat tenderness, stress relaxation times from stress decay curves were measured. Sixteen strip loins with a wide range in shear force values were obtained from 8 electrically-stimulated, A-maturity beef carcasses ranging in USDA Beef Quality grades from Select to Low Choice at Texas A&M University. The stress relaxation characteristics of the beef samples were tested from thawed 8 mm thick steaks at 10% strain level at room temperature (22oC) using an Instron Universal Testing machine equipped with a 30 mm diameter probe, and Warner-Bratzler shear force (WBSF) values were measured from the mirror image steaks. Changes in the stress relaxation curve between 70 and 50% of the maximum stress differed as the meat became tougher and we could predict WBSF with about 40% accuracy. However, prediction power was lower from other mathematical calculations that accounted for changes in the entire stress relaxation curve and a measurement of initial maximum force (the force the probe detected upon compression). Fitting the whole curve into an equation may overshadow the critical region representing beef shear force in the stress-relaxation curves. Also, it was very difficult to find a single representative model to fit the decay curves with different WBSF data because the beef samples showed viscoelastic non-linearity at high strain. Thus, extracting the information from specific distinguished regions in stress-relaxation curves may provide a method to account for variation in WBSF and thus, this information could be used in developing automated methods to predict beef tenderness.
Session 30C, Muscle Foods: Tenderness, Quality, Processing, Marination, Oxidation, and Shelf-Life
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