TENDERNESS CLASSIFICATION OF BEEF .1. EVALUATION OF BEEF LONGISSIMUS SHEAR FORCE AT 1 OR 2 DAYS POSTMORTEM AS A PREDICTOR OF AGED BEEF TENDERNESS

The present experiments were conducted to evaluate the use of longissi mus shear force at 1 or 2 d postmortem as a predictor of beef longissi mus shear force at 14 d postmortem. Experiments 1 (n = 400) and 2 (n = 554) included carcasses slaughtered and processed under laboratory an d commercial conditions, respectively. A carcass was < classified as ' 'tender,'' ''intermediate,'' or ''tough'' if its longissimus shear val ue at 1 or 2 d postmortem was < 6 kg, 6 to 9 kg, or > 9 kg, respective ly. For Exp. 1 and 2, large (P < .001) differences existed between eac h successive tenderness class in mean shear force at 14 d postmortem. Moreover, frequency analysis indicated that tenderness classification accurately (84.8 and 94.8% for Exp. 1 and 2, respectively) predicted w hether the sample would have a ''low'' (< 6 kg) Warner-Bratzler shear (WBS) value at 14 d postmortem. All (100%) of the carcasses in the ''t ender'' class had ''low'' WBS values at 14 d postmortem, most (81 and 85% for Exp. 1 and 2, respectively) of the carcasses in the ''intermed iate'' class had ''low'' WBS values at 14 d postmortem, and most (74 a nd 67% for Exp. 1 and 2, respectively) of the carcasses in the ''tough '' class did not have ''low'' WBS values at 14 d postmortem. Although shear force at 2 d postmortem was only moderately correlated (r = .68) with shear force at 14 d postmortem, 68% of the carcasses sampled in Exp. 2 could be guaranteed tender with 100% accuracy based on shear fo rce at 2 d postmortem. Thus, cooked beef longissimus shear force can b e measured at 1 or 2 d postmortem and used to predict longissimus tend erness after cooler aging (14 d postmortem) with a relatively high deg ree of accuracy.