Metabolomic investigation of tenderness and aging response in beef longissimus steaks

Authors: King, David - Andy; Shackelford, Steven; BROECKLING, COREY - Colorado State University; PRENNI, JESSICA - Colorado State University; BELK, KEITH - Colorado State University; Wheeler, Tommy

Submitted to: International Congress of Meat Science and Technology Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/30/2018
Publication Date: 8/12/2018
Citation: King, D.A., Shackelford, S.D., Broeckling, C.D., Prenni, J.E., Belk, K., Wheeler, T.L. 2018. Metabolomic investigation of tenderness and aging response in beef longissimus steaks. In: Proceedings of the International Congress of Meat Science and Technology. Melbourne, Australia, 12-17 Aug. 2018. Session 10. Available: http://icomst-proceedings.helsinki.fi/papers/2018_10_05.pdf

Interpretive Summary:

Technical Abstract: I. INTRODUCTION Substantial investment has been made in understanding biochemical factors affecting beef tenderness. Component traits such as sarcomere length and postmortem proteolysis have been used to expand understanding of mechanisms responsible for animal variation in beef tenderness and the extent of the aging response. However, component traits explain a limited amount of the variation in tenderness, and sometimes fail to characterize tenderness differences. Thus, the present experiment was conducted to identify metabolomic biomarkers explaining differences in beef tenderness and potential relationships between these biomarkers and sarcomere length and desmin degradation. II. MATERIALS AND METHODS Carcasses (U.S. Select: n = 30) were selected to represent extremes in tenderness using the tenderness prediction model in the VBG2000GigE beef grading system. Beef, loin, strip loin subprimals were obtained from the left side of each carcass. Steaks from each of the anterior and posterior halves of the longissimus lumborum, 4 pairs of adjacent steaks were blocked by location and assigned to be aged until 2, 7, 14, or 28 days postmortem. Thus, two pairs of steaks from each strip loin were assigned to each aging time. One steak from each pair was designated for slice shear force determination and the other was designated for biochemical analysis. Slice shear force was accomplished using an established protocol[1]. Steaks designated for biochemical analysis were used for sarcomere length determination[2], quantification of desmin degradation[3], and non-targeted LC and GC/MS metabolite profiling[4]. Slice shear force values from all aging times were utilized to identify the carcasses with the lowest (most tender) and highest (toughest) slice shear force values (n = 10 per group). Analysis of variance and correlation analysis were used to identify metabolites that were strongly related (P-values exceeding 2 X 10-5) to slice shear force, desmin degradation, and sarcomere length. Metabolites exceeding these criteria were included in partial-least squares regression analysis with slice shear force, desmin degradation, and sarcomere length as dependent variables, and tenderness class and aging time as fixed effects. III. RESULTS AND DISCUSSION Steaks classified as tough had higher (P < 0.001) slice shear force values than steaks classified as tender. Increasing aging time decreased (P < 0.001) slice shear force values. Steaks from carcasses classified as tender on d 2 postmortem had slice shear force values similar (P = 0.42) to those of steaks from carcasses classified as tough on d 28 postmortem. Steaks classified as tender had a greater (P<10-4) proportion of desmin degraded than steaks from carcasses classified as tough. Increasing aging time increased (P < 10-22) the amount of desmin degraded in steaks from both tenderness classes. Sarcomere length did not differ across tenderness classes or aging times. A total of 113 metabolites with P-values exceeding the Bonferroni correction level (P < 2 × 10-5) in analysis of variance and correlation analyses were included in further analyses. No metabolites met this level of significance for correlation to sarcomere length, so an additional 6 metabolites were included based on partial correlations significant at (P < 0.01). Thirty-six metabolites that met the screening criteria could be annotated and some were loosely categorized into amino acids/peptides (n = 16), metabolism intermediates (n = 7), glycosides (n=4), fatty acids and phospholipids (n =3). Each of the amino acids increased (P < 10-5) with increased aging time and generally were present in greater (P < 0.05) levels in steaks classified as tender. Metabolites classified as glycosides increased (P < 10-5) with increased aging time. Levels of three compounds with masses suggestive of plant glycosid