Multivariate examination of metabolic contributions to beef longissimus lumborum flavor

Authors: King, David - Andy; MILLER, RHONDA - Texas A&M University; MCKEITH, RUSSEL - Texas A&M University; GRAYSON, ADRIA - Texas A&M University; Shackelford, Steven; GEHRING, KERRI - Texas A&M University; SAVELL, JEFF - Texas A&M University; Wheeler, Tommy

Submitted to: Meat and Muscle Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2024
Publication Date: 3/8/2024
Citation: King, D.A., Miller, R.K., McKeith, R.O., Grayson, A.L., Shackelford, S.D., Gehring, K.B., Savell, J.W., Wheeler, T.L. 2024. Multivariate examination of metabolic contributions to beef longissimus lumborum flavor. Meat and Muscle Biology. 8(1). Article 17055. https://doi.org/10.22175/mmb.17055.
DOI: https://doi.org/10.22175/mmb.17055

Interpretive Summary: The dark cutting beef condition is caused by a lack of pH decline due to the depletion of muscle energy stores and has profound effects on beef quality attributes, in particularly flavor. However, little work has related the metabolic differences resulting in the dark cutting condition to flavor development in those muscles. This study used a multivariate approach of data analysis to capture the relationships among flavor attributes as well as the relationships of these flavor attributes to measures of muscle metabolism in carcasses with varying severity of the dark cutting condition. The results indicated that while muscle pH does reflect differences in muscle metabolism, pH alone does not fully characterize these differences. Variation in the capacity and extent of muscle metabolism affects flavor development and more work is necessary to separate the effects of metabolic contributions to flavor an direct effects of muscle pH to flavor.

Technical Abstract: We examined the impact of muscle metabolic capacity on beef flavor. Beef carcasses were selected to have normal or dark cutting lean color (n=160, each) and aged until 13 d postmortem.Muscle pH, glycolytic potential, mitochondrial DNA copy number, instrumental lean color, myoglobin concentration, carbonyls on sarcoplasmic proteins, initial metmyoglobin formation, bloom, proximate composition, slice shear force, sarcomere length, desmin degradation, overall tenderness, juiciness, and flavor profile were determined. Carcasses were clustered based on metabolic characteristics into dark cutting classes (Control, Shady, Moderate, and Severe), which were compared using analysis of variance and multiple factor analysis. Clusters were in general, but not complete, agreement with classifications based on muscle pH. Multiple factor analysis produced two dimensions that explained 30.8% and 13.8% of the variation, respectively. Dimension 1 had strong negative loadings for muscle pH and strong positive loadings for glycolytic potential, L*, a*, b*, initial metmyoglobin formation, and bloom. Ratings for fat-like, overall sweet, sweet, musty/earthy/hummus had relatively weak positive loadings for dimension while salt, sour, and metallic ratings had weak negative loadings for dimension 1. Overall tenderness and juiciness ratings, marbling score, intramuscular lipid content, carbonyls on sarcoplasmic proteins, and L* had positive loadings for dimension 2. Ratings for fat-like, beef flavor identity, and brown/roasted had positive loadings for dimension 2, and intramuscular moisture content, slice shear force, and mitochondrial copy number had negative loadings. Sample scores stratified dark cutting clusters along dimension 1, which agreed with univariate comparisons for these traits. Sample scores for dimension 2 were greater for Moderate and Control steaks than for Shady steaks. These data indicate that clustering was effective in segmenting them into groupings more indicative of the metabolic machinery than pH alone. Moreover, these metabolic differences influenced animal variation in beef flavor profile.