PSV-4 Proteomics and Metabolomics Profiling of Meat Exudate to Understand the Impact of Postmortem Aging on Oxidative Stability of Beef Muscles
Authors: Setyabrata Derico , Ma Danyi , Xie Shaojun , Thimmapuram Jyothi , Cooper Bruce , Aryal Uma , Kim Brad H B 
Published: October 2023

Abstract
The objectives of this study were to characterize the meat exudate proteome and metabolome composition that may be related to the color and oxidative stability of beef muscles during aging. Beef longissimus lumborum (LD) and psoas major (PM) muscles from seven carcasses were obtained at 2 d postmortem. Each muscle was cut into three sections, vacuum packaged and assigned into three aging periods (9, 16 and 23 d). At the end of each aging period, the exudate was collected from each sample and immediately frozen for both proteomics and metabolomics analyses. Steak cuts were made for display color and oxidative stability analyses. Exudate samples were prepared and analyzed using the UPLC-ESI-MS for metabolomics profiling and HPLC-MS/MS for proteomics analyses. The metabolites were annotated using the HMDB database, and proteins were compared with the UniProt database. The relative abundance of the metabolites and proteins was quantified and normalized for statistical analysis. Both proteomes and metabolites were analyzed using ANOVA (P &lt; 0.05). Principal component analysis (PCA), hierarchical cluster analysis (HCA) and correlation test between color and lipid oxidative stability and metabolites/proteins were performed. Untargeted protein profiling identified a total of 737 proteins from the meat exudate, of which 222 proteins were affected by the treatments (P &lt; 0.05). PCA analysis indicated an apparent clustering of the proteins, mainly separating the cluster by the muscle types. A greater number of oxidative metabolism enzymes was identified in PM exudate, while more glycolytic metabolism enzymes were identified in LD exudate. Additionally, a greater abundance of cytochrome c was observed in PM muscle exudate along with laminin proteins, indicating a greater extent of degradation in the muscle, potentially explaining the lower oxidative stability of PM muscle. A total of 518 metabolite features was detected from the meat exudate using untargeted metabolomics analysis, in which 167 features were affected by the treatments (P &lt; 0.05). The PCA analysis exhibited a distinct grouping of the treatments, separating not only muscle types but also the aging periods. Greater antioxidant compounds, such as carnitines and glucosides, were identified in LD muscle exudate. A greater number of lipid and nucleotide metabolites were also observed in LD exudate and 23d exudate. HSP70 and laminin proteins, along with glucosides metabolites identified in the exudates, which were significantly correlated (r &gt; 0.5) to muscle color and oxidative stability. The current results indicated that meat exudate could be a viable analytical matrix to understand oxidative stability and protein degradation of muscles during aging. The proteomics and metabolomics profiling identified specific compounds in meat exudate that could be related to different oxidative stability of beef muscles. Further research should be warranted to validate the identified compounds as potential biomarkers to predict oxidative stability and quality attributes of specific muscles during aging.