Beef Color Difference Mechanism Of Different Ultimate PH Values During Early Postmortem Based On Sarcoplasmic Proteomics

With the rise of China's beef production and consumption,the producers and consumers pay more attention to the quality.Meat color is a major quality attribute that influences the purchasing decisions of consumers at the point of sale.However,there is a kind of purple black heterogeneous meat,which is known as DFD(Dark,Firm & Dry)meat or dark cutting beef.DFD meat color makes the consumers feel not fresh,so the price is greatly reduced.At present,the mechanism of the color formation of DFD meat is still not clear.The metabolism of beef muscle during the early postmortem is very complicated.Not only it was involved the glycolysis process,the formation of ultimate pH value,but also it was involved variety of redox system and a variety of enzyme regulation system.It is the most prosperous stage of post-mortem metabolism.It is critical stage to study the beef color difference mechanism of different ultimate pH values during early postmortem.Proteomics and bioinformatics analysis could be a single substance with the idea of systematic research.It was from a new point of view a comprehensive explanation of the problem,which was associated with the meat color.It could effectively compare the differences ultimate of pH value of beef in a number of metabolic pathways.It was an important way to identify the key biomarker proteins associated with the formation of meat color and to determine the mechanism of color formation during the early postmortem.In this study,I selected 9 heads of cattle(Luxi Yellow Cattle and Simmental Crossbred Progeny),and the age and weight is nearly.The pH values of raw steak samples were determined at 45 min,3 h,6 h,12 h and 24 h after slaughter.This study compared gel images of the same postmortem time in different ultimate pH groups(low ultimate pH group:5.40<pH?5.80;intermediate ultimate pH group: 5.80 <p H?6.10;high ultimate pH group: pH> 6.10)and the same ultimate pH group at different postmortem.At last,the key differential proteins were closely related to the formation of different meat color at the early postmortem time,and the differentially expressed proteins were analyzed by bioinformatics such as Gene Ontology,KEGG Pathway and Protein-protein Interaction.The results showed that the main differential proteins that influence the difference of beef flesh color in different p H value groups were molecular chaperone protein(HSPB1 protein,Alpha-crystallin B chain,heat shock protein beta-1)and the enzymes associated with glycolysis processes and energy metabolism(creatine kinase M chain,adenylate kinase 1,phosphoglucomutase 1 etc.).These proteins maybe involved in the anaerobic respiration,ATP metabolism and the post-translational modification process,which change the body environment and may be sever as the candidate predictors for the monitoring of different pH values at different postmortem time.The results showed that some antioxidant proteins(peroxiredoxin 1,peroxiredoxin 2,antioxidant proteins)were found in the same ultimate pH group with the change of postmortem time.A variety of glycolytic processes and energy metabolism related enzymes(succinate-CoA ligase,pyruvate dehydrogenase E1-? subunit,glucose phosphate Mutant enzyme 1,etc.)were also be found.These key differential proteins were important enzymes involved in the glycolysis.They were related to the rate of anaerobic degradation of the glycogen,which is directly related to the process and the activity.The activity is closely related to the ultimate pH values.The differential proteins which were compared of the low ultimate pH value group at 45 minutes postmortem time and the high ultimate pH group postmortem times influence the color difference were antioxidant protein(peroxiredoxin 1,peroxiredoxin 2 etc.),molecular chaperone protein(HSPB1 protein,Alpha-crystallin B chain,heat shock protein B6 etc.)and other enzymes(inorganic pyrophosphate phosphatase,non-selenium glutathione phospholipid hydroperoxide peroxidase,phosphoglucomutase 1 etc.).These differential proteins were likely involved in the regulation of postmortem cell body of oxidative stress and the redox regulation process,which indirectly leaded to its color differences.