MARC Beef Classification System

The development of technologies that could be used by the U.S. beef packing industry to accurately characterize beef for tenderness has been a major focus of this laboratory. Because longissimus comprises a higher proportion of total carcass value than any other muscle and there is more carcassto-carcass tenderness variation in longissimus than any other major beef muscle (Shackelford et al., 1995, 1997a), the need for tenderness classification is greatest for longissimus. Ideally, the beef industry would prefer to be able to measure (predict) meat tenderness with a rapid, automated, tamperproof, noninvasive, accurate instrument. It is highly unlikely that indirect measurements will ever be sufficiently accurate, and more importantly, amenable to industry application. Therefore, we have focused on methodology for direct measurement of tenderness. The best direct measure of tenderness with the best chance to be successfully adapted for automated, on-line tenderness measurement was Warner-Bratzler shear force, an objective measurement of meat tenderness routinely used by meat scientists. Shackelford et al. (1997b) determined that a high proportion of the variation in longissimus Warner-Bratzler shear force at 14 days after slaughter could be predicted by measuring shear force at 1 or 2 days after slaughter. Although there is a large amount of variation in the extent to which carcasses tenderize during the aging period, a large portion of that variation could be predicted by measuring shear force at 1 or 2 days after slaughter (Shackelford et al., 1997b). Thus, Warner-Bratzler shear force measurement was adapted for commercial use (Shackelford et al., 1999).