Color Stability and Tenderness Attributes of Beef Longissimus Lumborum Steaks at 2 Different Aging Periods Are Impacted by Metabolic Characteristics

Beef color and tenderness are 2 of the most important attributes contributing to the perception of meat quality and palatability. Studies in search of biomarkers explaining mechanisms regulating meat color stability and tenderness have identified biology in common with both traits. Therefore, the objective of this study was to evaluate the contribution of metabolic factors to animal variation in beef longissimus lumborum tenderness and color stability. Beef carcasses (n = 96) were selected based on tenderness and color stability predictions at grading. Longissimus lumborum muscles were obtained from both sides of each carcass and aged until 12 or 26 d postmortem. Overall tenderness ratings, slice shear force, desmin degradation, and sarcomere length were used to characterize tenderness. Instrumental color values measured during simulated retail display, oxygen consumption, and nitric oxide metmyoglobin-reducing ability were used to characterize color stability. Metabolic traits including pH, glycolytic intermediates, proportion of Type I fibers, sarcoplasmic and myofibrillar carbonyls, and myoglobin concentration were determined on each muscle. Relationships of metabolic traits to tenderness and color stability were assessed with correlation analysis, analysis of variance across clusters derived from tenderness and color stability data, and principal component analysis. Increased nitric oxide metmyoglobin-reducing ability was associated with decreased (P < 0.05) tenderness ratings and desmin degradation and longer sarcomere lengths. Oxygen consumption was associated with decreased tenderness ratings and increased slice shear force (P < 0.05). Both tenderness and lean color stability were negatively related to increased oxidative metabolism. These results indicated that relationships exist between tenderness and lean color stability. Moreover, animal variation in both tenderness and color stability is influenced by muscle metabolism.