Date of this Version
Carcasses (n = 265) selected to differ in USDA yield grade were evaluated by expert graders and assessed for tenderness with the Tendertec Mark III Beef Grading Instrument. Tendertec measurements were collected on longissimus lumborum muscles in both sides of each carcass. During fabrication of each left carcass side, a rib section (later converted into three steaks) was removed for aging and subsequent sensory panel evaluation at 14 d and for Warner-Bratzler shear force measurements at 14 and 28 d. Correlation coefficients for repeatability of Tendertec output variables, between left and right carcass sides, were .57, .44, .70, and .65 for Area-2, Area-2B, Power-2, and Power-2B, respectively. Correlations between Tendertec output variables and Warner-Bratzler shear force evaluations performed on steaks aged 14 or 28 d were not different from zero. Sensory panel ratings for amount of connective tissue were correlated ( P < .01) with Tendertec output variables Area-2 and Area-2B (r = .168 and .154, respectively), and ratings for overall tenderness were correlated ( P < .05) with the Area-2 output variable (r = .131) but the coefficients were very low. Segregation analysis, using Tendertec output variables Area-2 and Power-2, significantly ( P < .05) stratified sensory panel ratings for connective tissue amount and overall tenderness. Even though the Tendertec probe detected some differences in connective tissue contributions to rib steak tenderness, it was not better than USDA quality grade at segmenting A-maturity carcasses into anticipated tenderness outcomes, and thus its applicability as a grading instrument may be limited to use on more mature beef carcasses.