Abstract: Objective: To explore the major cause for abnormal meat. Methods: At 45 min postmortem, chicken, pale soft exudative (PSE) pork, normal pork and beef were taken for the analysis of glycogen, ATP/ADP/AMP contents, lactate dehydrogenase (LDH) activity. At the same time, myofibrillar and sarcoplasmic proteins were extracted and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the bands of interest were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The difference in band intensity was evaluated. Results: Glycogen was higher in beef than three other meats (P < 0.05). Glycogen and ATP contents were higher in PSE pork than normal pork and chicken (P < 0.05). LDH activity in PSE pork was much higher than all other groups (P < 0.05). SDS-PAGE with ProQ staining indicated that, at 45 min postmortem, the phosphorylation levels of sarcoplasmic proteins from 6 bands were lower in PSE pork than those of normal pork (P < 0.05), while sarcoplasmic proteins from other 6 bands had higher phosphorylation levels than normal pork (P < 0.05). In addition, 3 bands in beef and 1 bands in chicken had lower phsophorylation levels, whilst higher phsophorylation levels were observed for 1 bands in beef and 8 bands in chicken. For myofibrillar proteins, the majority of bands in beef had highest phosphorylation levels, the lowest phosphorylation levels were found for chicken (P < 0.05), and pork was in the middle. Similarly, 7 bands in PSE pork had lower phosphorylation levels than normal pork (P < 0.05), while 6 bands had higher phosphorylation levels than normal pork (P < 0.05). Conclusion: The rates of glycolysis and ATP depletion, and LDH activity had a great contribution to PSE pork, which is also associated with protein phosphorylation of glycolytic enzymes.

Key words: abnormal meat, lactate dehydrogenase (LDH), glycolysis, energy metabolism