Tenderness beef strip loin subprimals and USDA quality grades as evaluated by slice shear force and Warner-Bratzler force values and the relationship between slice shear and Warner-Bratzler

Beef tenderness is one of the primary beef quality attributes affecting consumer satisfaction and effects consumer purchasing decisions. Two methods of tenderness analysis are currently being used in both research and the meat industry. The Warner-Bratzler shear (WBS) method of tenderness analysis is the traditional method that utilizes an average of six 1.27 - cm samples from a single steak to generate a tenderness value. The WBS method is accurate but does not provide rapid results that could be utilized in a production setting to allow for tenderness based sorting of carcasses. A more recent method of analysis is the slice shear force (SSF) method which uses a single measurement from each steak and produces rapid results. The purpose of this study was to investigate the effect of steak location within a strip loin subprimal (IMPS 180) on SSF and WBS values and muscle fiber angles, the effectiveness of USDA quality grades on predicting beef tenderness as well as evaluate the relationship between SSF and WBS values. The study was conducted in two phases, phase one focused on the effect of steak location, the efficacy of USDA quality grades as a predictor of meat tenderness, and muscle fiber angle on SSF and WBS values. Fifteen USDA Top Choice, 15 Choice, 15 Select, and 15 no roll strip loin subprimals were fabricated into 12, 2.54 cm steaks and measured using SSF and WBS methods. Slice shear force measurements were obtained from the lateral and medial portion of each steak. Warner-Bratzler shear force measurements were obtained at the lateral, middle and medial sections. Phase two consisted of the evaluation of 1,538 2.54 - cm USDA Choice and Select strip loin steaks to determine the correlation between SSF and WBS measurements. Slice shear force measurements were obtained from the lateral and medial sections of each steak and WBS values were obtained from the lateral, middle and medial portions of each steak. Steak location within a strip loin subprimal had a significant effect on both SSF and WBS values (P < 0.001) with a linear increase in tenderness values as steak location moved closer toward the posterior end of the strip loin. The SSF method produced similar results in location 1 through 8, and WBS values were similar from steak locations 1 through 5 (P > 0.05). Furthermore, this study shows that USDA quality grade has a significant effect on beef tenderness (P < 0.002) when evaluated using SSF and WBS protocols. This study found that no differences in tenderness exists between USDA Select and no roll quality grades. The muscle fiber angle changes in steaks throughout a strip loin. A significant difference in the lateral muscle fiber angle occurred at steak location 7 indicating that SSF may not produce accurate results at this location. Finally, significant correlations between SSF and WBS values were obtained in this study. Slice shear force from the lateral portion correlated to the averaged WBS values produced a correlation coefficient (r) of 0.636 and a correlation of an averaged SSF value comprised of values obtained from the lateral and medial sections to an averaged WBS value produced a correlation coefficient (r) of 0.704.