The Effects Of Tenderness Mechanism By Modifying The Rate Of Post-mortem Cattlemuscle Metabolism

The aim of this study was to investigate the changes in physico-chemical properties that occur afteradjusting postmortem chilling temperatures in beef. The left sides of beef carcasses were used as controls,chilled for24h at2℃. The right sides were chilled for4h at2℃,4h at10-15℃, and16h at2℃. Afterslaughter，the temperatures，pH, nuleotides compounds, μ-calpain, m-calpain and calpastain activities weremeasured at0,4,8,12and24h, respectively. In addition,1,3,7days after slaughter, cold, heat and totalshortening，drip, cooking and total loss，shear force were determine. We seen from the results, it took8h forthe control carcasses to cool down to approximately10°C and13h for the treatment carcasses. Treatment hadlowered pH than the control at8h, treatment muscles at8h postmortem had lowered ATP content than thecontrol (P <0.05), changes in treatment of pH and ATP content suggests that adjusting postmortem chillingtemperatures is a set of biochemical metabolism process accelerated phase. The shear force in treatmentcarcasses at day1was similar to that of the control at day7, treatment carcasses at day7was similar to that ofthe control at day21. However, the objective of μ-calpain, m-calpain and calpastain activities is that have nochanges, there may be other factors led to the tender meat changes in different chilling temperatures. We seenfrom the results, adjusting postmortem chilling temperatures can effectively avoid the cold shrinking and havesignificantly shorten the beef meat tenderizer. But we could observe that the μ-calpain, m-calpain, calpastainactivities were no significant differences in treatment and control. In order to further understand themechanism of meat tenderizer,2-DE is used to analyze proteome differential expression in beef longissimusdorsi muscle use of two differents post-slaughter handling procedures, show that some protein hydrolysis canoccur in different postmortem chilling, and has no relationship with the calpain, meanwhile, the main factors ininfluencing tenderness differences may be due to other enzymes.