Date of Award
Master of Science
Food Science and Technology
J.L. McCarty, R.R. Shrode
The L. E. E.-Kramer and Warner-Bratzler shearing cells were Installed in an Instron Universal Testing Instrument (Instron). Reproducibility of the two devices was established by the use of frankfurters as a "standard" meat sample. Five beef muscles, the Longissimus dorsi (ribeye), L. dorsi (loin), Semimembranosus, Semitendinosus and Biceps femoris were evaluated objectively and subjectively.
Three crossheads speeds, 5, 10 and 20 inches per minute, and two types of frankfurters, all-meat and all-beef were used to determine the reproducibility of the devices. The coefficient of variation was used as a criterion to detect variability. It was found that all-meat frankfurters sheared at a crosshead and recorder speed of ten inches per minute gave acceptable coefficients of variation of 2.74 percent for the Kramer device and 2.94 percent for the Warner-Bratzler device.
One-half inch diameter cores, perpendicular and parallel to the orientation of the muscle fibers were used in the objective measurements and a trained, five member taste panel evaluated the cooked muscles. Bricks ½ x ½ x 1 inch parallel to the fiber and bricks ½ x ½ x 2 inches perpendicular to the fiber were used in evaluation of raw muscles.
Shear values were obtained using both devices installed in the Instron. A crosshead and recorder speed of 10 inches per minute with a full scale of twenty pounds for the Kramer device and ten kilograms for the Warner-Bratzler device were used. From the force-distance curves recorded by the Instron, the parameters of maximum force and area under the curve (work) were evaluated. The following inferences were made:
a. Differences between the two devices were statistically significant (P<0.05).
b. Both devices gave significant coefficients of simple correlation between their respective shear values and panel scores.
c. Both devices gave poor correlation between shear values and panel scores when between muscle covariation was removed by an analysis of covariance.
d. Differences between muscles with respect to panel scores were statistically significant (P<0.05). .
e. Differences between muscles with respect to shear values were statistically significant (P<0.05).
f. Both devices gave poor response on raw muscle.
Corrick, Harriet Perry, "Tenderness of beef muscle measured by shear-stress. " Master's Thesis, University of Tennessee, 1968.