Elsevier

Journal of Proteomics

Volume 271, 16 January 2023, 104756
Journal of Proteomics

Early postmortem muscle proteome and metabolome of beef longissimus thoracis muscle classified by pH at 6 hours postmortem

https://doi.org/10.1016/j.jprot.2022.104756Get rights and content

Highlights

  • A lower 6 h postmortem pH was linked to more tender steaks at 1 day postmortem.

  • More tender steaks were explained by greater calpain-1 autolysis and desmin degradation.

  • Greater energetic metabolites and enzymes were identified in the low pH classification.

  • Greater onset of apoptosis was observed in the more tender, low pH classification.

Abstract

The objective was to identify metabolome and proteome differences at 1 h and 1 d postmortem between longissimus thoracis (LT) muscle classified based on 6 h pH values. Twenty beef LT rib sections were sorted based on 6 h postmortem pH values into low (LpH; pH < 5.55; n = 9) and high (HpH; pH > 5.84; n = 8) pH classifications. Warner-Bratzler shear force (WBSF), desmin degradation, and calpain-1 autolysis were measured. Two-dimensional difference in gel electrophoresis (3–10, 4–7, and 6–9 pH range) and Tandem mass tagging (TMT) protein analyses were employed to determine how the sarcoplasmic protein profile varied across pH classification. Non-targeted metabolomic analyses were conducted on extracts prepared at 1 h and 1 d postmortem. The LpH classification had a lower WBSF value at 1 d postmortem, which was explained by greater calpain-1 autolysis and desmin degradation at 1 d postmortem. Proteome and metabolome analysis revealed a phenotype that promotes more rapid energy metabolism in the LpH group. Proteome and metabolome analyses identified energy production, apoptotic, calcium homeostasis, and proteasome systems influencing pH classifications that could explain the observed pH, proteolysis, and beef tenderness differences.

Significance

This study is the first to identify proteomic and metabolomic variations early (1 h and 1 day) postmortem that are linked to differences in early (6 h) postmortem pH values and to tenderness differences at 1 day postmortem. This study integrates postmortem biochemical features (protein degradation, proteome, and metabolome variations) to postmortem pH decline and eating quality of beef steaks. Potential biomarkers of more rapid postmortem metabolism linked to earlier tenderization in beef are suggested. Identification of these biochemical features will assist in predicting the eating quality of beef products.

Introduction

Fresh beef tenderness is one of the most important purchasing motivators for consumers [1]. Consumers are willing to pay a premium for beef products with consistent, excellent eating quality [2]. However, tenderness determination is one of the most complex facets of meat quality and is influenced by a variety of factors, including the rate and extent of pH decline [[3], [4], [5]], sarcomere length [6], postmortem protein degradation [[5], [6], [7]], and the collagen content [8] of beef products.

No rapid, reliable, and non-destructive methods exist to predict beef tenderness. Utilizing rapid, non-destructive methodologies to predict the eating quality of beef is one of the forefront goals of the beef industry. Predicting beef tenderness would improve the ability to provide a premium market for beef products and provide a better eating experience for consumers. The ability to predict product that is tender earlier would allow earlier sorting into premium markets. A robust application to predict beef tenderness has not been identified and must be established through molecular profiles (metabolites and proteins). Recent meta-analyses have characterized differences in muscle protein profiles in meat that differed greatly in tenderness. Specifically, abundance and post-translational modification of some proteins involved in muscle contraction, muscle structure, energy metabolism, heat stress, and oxidative stress have potential to explain variations in meat tenderness [9,10]. Therefore, understanding how postmortem metabolism establishes the conditions that impact the rate and extent of tenderness development is essential to predicting tenderness differences in beef products.

Postmortem pH decline of beef influences beef tenderness by affecting protein solubility and protein degradation [3,5,11]. Beef with a more rapid rate of pH decline compared to a slower rate of pH decline tends to result in more tender beef at 1 d postmortem [3,5,12]. Marsh et al. [3] showed that the most tender aged (≥14 d aging) beef longissimus muscle had intermediate (6.0–6.3 pH at 3 h) pH values at 3 h postmortem. Glycolytic enzymes and other metabolic proteins have been identified as potential biomarkers of beef tenderness [9]. The rate of postmortem glycolysis through abundances of glycolytic enzymes can impact pH decline, thus impacting tenderness development [10,13]. Understanding how energy metabolism and the resulting pH decline set the stage for meat quality development is integral to predicting tenderness variations in beef.

The objective of this study was to test the hypothesis that the metabolome and the sarcoplasmic muscle proteome are related to the rate of early postmortem metabolism. To achieve this objective, muscle pH at 6 h postmortem was used as a metric to categorize the rate of metabolism. Because we wanted to have as much variation in early postmortem pH as possible, we used longissimus dorsi samples that were collected in a previous study [5]. These samples varied widely in their pH values at 6 h postmortem making them the ideal population to test the hypothesis proposed in the current study. This study provides valuable information that aids in identifying novel chemical phenotypes to inform the pursuit of biomarkers of postmortem metabolism impacting tenderness development.

Section snippets

Sample selection

Samples were collected from carcasses of cattle that were fed as previously described [5]. Samples were selected for inclusion in the current study on the basis of pH value at 6 h postmortem. Samples were classified as low pH (LpH) at 6 h or high pH (LpH) at 6 h postmortem (LpH; n = 9; pH at 6 h postmortem <5.55 and HpH; n = 8; pH at 6 h postmortem >5.84) Temperature, pH (1, 3, 6, and 24 h postmortem), and Warner-Bratzler shear force (WBSF; 1, 3, 7, and 14 d postmortem) were measured as

Results and discussion

The study objective was to categorize a subset of cattle {as described by Schulte et al. [5]} by metabolic rate and chemical phenotypes in an effort to identify biomarkers of early postmortem metabolism in these samples. Therefore, the results are aimed at identifying phenotypes of rapid metabolism.

Conclusions

Classification by pH values at 6 h postmortem resulted in significant differences in quality characteristics. The LpH classification had lower WBSF values at 1 d postmortem, which was explained by greater calpain-1 autolysis, desmin degradation, and troponin-T degradation at 1 d postmortem. The LpH classification had greater abundances of energy production enzymes and metabolites at 1 h identified in glycogenolysis, glycolysis, and the tricarboxylic acid cycle. Greater energy metabolites and

Acknowledgements

This work was supported by the Agriculture and Food Research Initiative (AFRI) grant no. 2018-67015-27546/project accession no. 1015001 from the USDA National Institute of Food and Agriculture.

References (64)

  • M.M. Pike et al.

    Quadratic relationship between early-post-mortem glycolytic rate and beef tenderness

    Meat Sci.

    (1993)
  • O.H. Voss et al.

    Binding of caspase-3 prodomain to heat shock protein 27 regulates monocyte apoptosis by inhibiting caspase-3 proteolytic activation

    J. Biol. Chem.

    (2007)
  • D. Lomiwes et al.

    Small heat shock proteins and their role in meat tenderness: a review

    Meat Sci.

    (2014)
  • Z. Li et al.

    Dephosphorylation enhances postmortem degradation of myofibrillar proteins

    Food Chem.

    (2018)
  • Z. Ding et al.

    Influence of oxidation on heat shock protein 27 translocation, caspase-3 and calpain activities and myofibrils degradation in postmortem beef muscles

    Food Chem.

    (2021)
  • A. Ouali et al.

    Biomarkers of meat tenderness: present knowledge and perspectives in regards to our current understanding of the mechanisms involved

    Meat Sci.

    (2013)
  • C.M. Dreiza et al.

    The small heat shock protein, HSPB6, in muscle function and disease

    Cell Stress Chaperones

    (2010)
  • D. Ma et al.

    Proteolytic changes of myofibrillar and small heat shock proteins in different bovine muscles during aging: their relevance to tenderness and water-holding capacity

    Meat Sci.

    (2020)
  • B. He et al.

    Enhancing muscle membrane repair by gene delivery of MG53 ameliorates muscular dystrophy and heart failure inδ-sarcoglycan-deficient hamsters

    Mol. Ther.

    (2012)
  • M. Gagaoua et al.

    Reverse phase protein arrays for the identification/validation of biomarkers of beef texture and their use for early classification of carcasses

    Food Chem.

    (2018)
  • D. Dutaud et al.

    Bovine muscle 20S proteasome. II: contribution of the 20S proteasome to meat tenderization as revealed by an ultrastructural approach

    Meat Sci.

    (2006)
  • J.M. Peters et al.

    Distinct 19 S and 20 S subcomplexes of the 26 S proteasome and their distribution in the nucleus and the cytoplasm

    J. Biol. Chem.

    (1994)
  • A.K. Wilfong et al.

    The effect of branding on consumer palatability ratings of beef strip loin steaks

    J. Anim. Sci.

    (2016)
  • M.D. Schulte et al.

    The influence of supranutritional zinc and ractopamine hydrochloride supplementation on early postmortem pH decline and meat quality development of beef

    Meat Muscle Biol.

    (2021)
  • E.M. England et al.

    Postmortem titin proteolysis is influenced by sarcomere length in bovine muscle

    J. Anim. Sci.

    (2012)
  • E. Huff-Lonergan et al.

    Proteolysis of specific muscle structural proteins by mu-calpain at low pH and temperature is similar to degradation in postmortem bovine muscle

    J. Anim. Sci.

    (1996)
  • T. Nishimura et al.

    Relationships between physical and structural properties of intramuscular connective tissue and toughness of raw pork

    Anim. Sci. J.

    (2009)
  • K.B. Carlson et al.

    Proteomic features linked to tenderness of aged pork loins

    J. Anim. Sci.

    (2017)
  • K.B. Carlson et al.

    Postmortem protein degradation is a key contributor to fresh pork loin tenderness

    J. Anim. Sci.

    (2017)
  • J.L. Melody et al.

    Early postmortem biochemical factors influence tenderness and water-holding capacity of three porcine muscles

    J. Anim. Sci.

    (2004)
  • A. Thompson et al.

    Tandem mass tags: a novel quantification strategy for comparative analysis of complex protein mixtures by MS/MS

    Anal. Chem.

    (2003)
  • C. Zhai et al.

    Tandem mass tag labeling to characterize muscle-specific proteome changes in beef during early postmortem period

    J. Proteome

    (2020)
  • Cited by (5)

    View full text