Submitted to: International Congress of Meat Science and Technology Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 13, 2005
Publication Date: August 7, 2005
Citation: Eastridge, J.S., Solomon, M.B. 2005. A method to evaluate shear force measurements from various instruments. In: Proceedings of the 51st International Congress of Meat Science and Technology, August 7-12, 2005, Baltimore, Maryland. Paper No. T18. Interpretive Summary: The meat industry, particularly beef, has a high-priority goal to reduce tenderness variability and to establish standards for levels of guaranteed tenderness. An obstacle for achieving this goal is the inability to compare tenderness measurements from various instruments. The most widely used texture measurement of meat tenderness, in the US and globally, is the Warner-Bratzler shear force test. Shear force measurements can be obtained using a variety of texture measuring systems; however, at present there is no reliable or valid method to compare shear force test results. Comparable results are required in order to establish tenderness standards. Our objective was to develop a method, using gelatin gels as the test material, for evaluating whether results from different instruments were comparable. Five concentrations of gelatin gels that gave statistically repeatable shear force values were tested on six instruments. The plot of shear force versus gelatin concentration for each instrument was used to determine regression line parameters which were statistically analyzed to identify which lines were similar. If the regression line slopes were equal, results from those instruments were comparable and data could be adjusted to a common point by differences in the line intercept. This method proved to be an effective way to evaluate which shear force results were similar.
Technical Abstract: Many instruments are used for the Warner-Bratzler (WB) tenderness determination; however, it is difficult to determine whether results are comparable. Since meat itself is too variable to use for such evaluation, we propose using gels as a test material. Shear force was determined for five concentrations of gels (n=11 batches) using six texture measuring instruments. Gelatin (concentration range 12 to 38 percent) was mixed with plasticizer solution (30% w/v sorbitol, 10 percent v/v glycerol) to prepare gels. After hydration, gels were dissolved at 68 °C with the aid of sonication to prevent foaming. Melted gels were placed into a 1 cm thick form and refrigerated 18 hr before cutting into 1 × 1 cm strips. Strips were vacuum packaged, three per pouch, and refrigerated until use within 48 hr. During testing, strips were kept on a cold plate. Each of the three strips was sheared five times for n=15 values per instrument. The shear attachment on five instruments had blade thickness and inverted-V cutout specified for the WB test, while the blade of the sixth instrument was the dull edge of a disposable microtome knife mounted in a razor blade jig. Instruments were randomly identified as A, B, C, D, E and F, and regression analysis of the shear force by gel concentration was performed to determine intercept, slope and R2 values for instrument comparisons. The relationship of gelatin concentration and shear force was highly significant, and texture instrument results were highly correlated to each other. The slope of the lines B, C, D and E, was not different (p > 0.05), indicating that data from these instruments could be compared after adjusting for differences (p < 0.001) in the intercept. Both slope and intercept for A, one of the older instruments, were significantly different from all others. The slope for F, which was acquired mid-experiment, differed from all other instruments except for B. By use of gels with a highly significant linear response for shear force, equal slopes of the regression line indicated which texture measurement systems were comparable.