Interactions among metabolic traits influencing beef longissimus lumborum and gluteus medius tenderness

Authors: King, David; Shackelford, Steven; Nonneman, Danny; Katz, Tatum; Wheeler, Tommy

Submitted to: Meat and Muscle Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2025
Publication Date: 6/1/2026
Citation: King, D.A., Shackelford, S.D., Nonneman, D.J., Katz, T.S., Wheeler, T.L. 2026. Interactions among metabolic traits influencing beef longissimus lumborum and gluteus medius tenderness. Meat and Muscle Biology. 10(1). Article 20241. https://doi.org/10.22175/mmb.20241.
DOI: https://doi.org/10.22175/mmb.20241

Interpretive Summary: Producing consistently tender beef has been an elusive goal. Several metabolic pathways function in beef muscles that affect tenderness. Indicator traits for these pathways have been identified as being related to tenderness variation, but previous results pertaining to these relationships to tenderness are inconsistent. Here, we investigated the relationships of metabolic traits to tenderness with a focus on the interactions among these traits that affect tenderness. Metabolic traits were used to build models predicting beef ribeye and top sirloin tenderness. Then, the interaction effects of each trait were tested. Interestingly, we demonstrated that the effect of one trait on tenderness could change dramatically depending on what was happening with the other traits. These traits interact in complex ways that influence beef tenderness. These findings bring new understanding of why some beef is more tender than others and could help producers create strategies to consistently deliver more tender meat.

Technical Abstract: This study was conducted to evaluate the effects of individual metabolic variables and their interactions on beef tenderness. Beef longissimus lumborum and gluteus medius muscles were obtained from beef carcasses (n = 100). On day 14 postmortem, slice shear force and trained sensory panel overall tenderness were determined. Muscle pH (48 h), and day 14 glycogen, glucose, glucose-6-phosphate, lactate, malate, myoglobin, proportion of type I fibers, protein solubility, thiobarbituric acid reactive substances, mitochondrial protein abundance, bloom, initial metmyoglobin formation, abundance of peroxiredoxin 2, abundance of heat shock protein 70, and carbonyls on sarcoplasmic, myofibrillar, and mitochondrial proteins were quantified. For each muscle, principal component analysis was used to derive a composite tenderness var­iable, combining slice shear force and overall tenderness ratings. Regression models tested relationships of each metabolic trait and their interactions on tenderness. Final models explained 97% and 88% of the deviance in composite tenderness for longissimus lumborum and gluteus medius steaks, respectively. The impact of individual variables and interactions on tenderness were evaluated by varying the values for the relevant variables while holding other variables constant. These results revealed that relationships of metabolic traits to tenderness differed across muscles, with more variables having curvilinear relationships to tenderness in longissimus lumborum steaks than in gluteus medius steaks. In both muscles, complex interactions among glycolytic metabolites, indicators of mitochondrial function, oxidative indicators, and chaperones influenced the contribution of each variable to tenderness. Moreover, the influence of component traits on tenderness was highly dependent on the metabolic status of the muscle. These results provide insight into the complexity of the biological basis for beef tenderness variation and provide impetus for future work in developing strategies to manage and improve beef tenderness.