Characterization of the Myofibrillar Proteome as a Way to Better Understand Differences in Bovine Meats Having Different Ultimate pH Values

Abstract

Influence of ultimate pH (pHu) on the occurrence of defective meats known as dark, firm, and dry (DFD) meats has been studied through a proteomic approach at early post‐mortem times. The myofibrillar sub‐proteome of longissimus thoracis et lumborum muscle from twelve loin samples from Asturiana de los Valles x Friesian yearling bulls, previously classified into two groups of six samples according to their pH values (normal, pHu < 6.0 and high, pHu ≥ 6.0), is analyzed at 24 h post‐mortem. Fractionation/enrichment of muscle samples is carried out by combining OFFGEL fractionation in the pH range 4–7 followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) of the retrieved liquid fractions. Four protein bands satisfactorily discriminate between meat samples with normal and high pHu. These bands are quantified by image analysis, and further identified by liquid chromatography‐mass spectrometry as desmin, pyruvate kinase, myosin light chain, and myosin heavy chain‐1 and ‐2. Coupling OFFGEL and SDS‐PAGE separation with MS provides detailed and reproducible myofibrillar protein profiles enabling comparison among the sample groups assayed. This makes feasible to identify biomarkers capable to better understand pre‐slaughter stress condition susceptible to give DFD meats with high pHu values.

Biomarkers and biosensors for the diagnosis of noncompliant pH, dark cutting beef predisposition, and welfare in cattle

“…A recent LC–MS/MS‐based proteomics study showed that proteins involved in glycogenolysis and mitochondrial electron transport may facilitate DC through increased oxygen consumption (Kiyimba et al., 2021). Unlike previous studies (Franco et al., 2015; Fuente‐Garcia et al., 2020), myosin light chain 1‐isoforms were not differentially abundant between high pH and normal beef. Another study revealed that glutaryl‐CoA dehydrogenase abundance has a strong correlation with DC and meat color, warranting further investigation (S. Wu et al., 2020).…”

“…Although this study identified protein biomarkers related to meat quality, the SDS–PAGE‐based electrophoretic separation approach may have obscured the identification of some differentially abundant proteins due to the potential co‐migration of various proteins in a single band. In another study, desmin, pyruvate kinase isoform X1, myosin light chain 1/3, and myosin 1 and 2 isoforms were identified as high pH bovine meat and preslaughter stress indicators (Fuente‐Garcia et al., 2020). A recent LC–MS/MS‐based proteomics study showed that proteins involved in glycogenolysis and mitochondrial electron transport may facilitate DC through increased oxygen consumption (Kiyimba et al., 2021).…”

New Insights on the Impact of Cattle Handling on Post-Mortem Myofibrillar Muscle Proteome and Meat Tenderization

“…Previous studies have shown that animals mixed during transport and lairage are more affected by pre-slaughter stress and they have also been related to higher post-mortem glycolytic metabolism [ 9 , 58 ]. Moreover, lower abundance of PKM was previously found in myofibrillar subproteome of high pH24 meat [ 26 ]. Thus, the lower levels of PKM found in the myofibrillar fraction of mixed animals in the present study can be explained by the glycogen depletion occurring due to PSS caused by the mixing procedure before slaughter.…”

“…The post-mortem concentration of these proteins has been previously associated with pork and beef tenderness [ 50 , 51 ], and belong to the robust list of biomarkers of beef tenderness shortlisted by Gagaoua et al [ 21 ]. Increased proteolysis of MYL1 has also been described in dark-cutting beef [ 22 , 26 ]. It is worthy to note that myosin lights chains were also identified as biomarkers of several beef color traits [ 47 ].…”

“…Since tenderness and color are considered as important beef quality traits for consumers., the impact of PSS on these attributes is worthy of investigation. Indeed, PSS is proven to have a detrimental effect due to the changes that induces in the enzymatic processes that, for example, induce the breakdown of myofibrillar structure mainly composed of structural and contractile proteins [ 23 , 24 , 25 , 26 ].…”