Tenderness classification of beef: II. Design and analysis of a system to measure beef longissimus shear force under commercial processing conditions

The objectives of this study were to evaluate the efficacy of a system for classifying beef for tenderness based on a rapid, simple method of measurin g cooked longissimus shear force. Longissimus steaks (2.54 cm thick) were t rimmed free of s.c. fat and bone and rapidly cooked using a belt grill. A l -cm-thick, 5-cm-long slice was removed from the cooked longissimus parallel with the muscle fibers for measurement of shear force. Slices were sheared with a flat, blunt-end blade using an electronic testing machine. The enti re process was completed in less than 10 min. Therefore, in commercial appl ication, this process could be completed during the 10- to 15-min period th at carcasses are normally held to allow the ribeye to bloom for quality gra ding, In Exp. I, the repeatability of slice shear force (SSF), as determine d by evaluation of duplicate samples from 204 A-maturity carcasses, was .89 . In Exp. 2, A-maturity carcasses (n = 483) were classified into three grou ps based on SSF (< 23, 23 to 40, and > 40 kg) at 3 d postmortem that differ ed (P < .001) in mean trained sensory panel tenderness ratings (7.3 +/- .04 , 6.4 +/- .06, and 4.4 +/- .20) and the percentages (100, 91, and 28%) of s amples rated "Slightly Tender" or higher at 14 d postmortem. Therefore, thi s tenderness classification system could be used to accurately segregate be ef carcasses into expected tenderness groups. Further research is needed to test the feasibility and accuracy of this system under a variety of commer cial processing conditions.