Effects Of Chilling Method And Electrical Stimulation On Postmortem Physical Chemical Properties And Quality Of The Cull Cow

The objective of part1of the study was to analysis and compare the effects of two chilling method onchanges of postmortem physicochemical characteristics of M. longissimus dorsi in cull cow. The left side werechilled for24h at2℃as control. The rightside were chilled for3h at2℃,6h at12℃,15h at2℃as treatment.The result showed that the core temperature of control has been reduced to4.1℃at10h postmortem. The coretemperature of treatment was maintained in the range of16±0.5℃at3-9h post-mortem, then reducedquickly from10h postmortem until4℃at13.5h postmortem. Treatment had low glycogen than control at8hand24h postmortem and had low pH value than control at8h postmortem significantly. This result showedthe glycogenolysis of treatment muscle was faster than control. Thus accelerated pH value reduction of thetreatment. Treatment muscle had longer sarcomeres than control at8h,24h,48h significantly. The shearforce of treatment was significantly lower than control at day1and day3. The result indicated cull cow weresustained chilling at2℃may result in severe cold shorting and had negative impact on the tenderness.Three-step chilling can improve the tenderness in cull cow.The objective of part2was of the study was to evaluate the changes of postmortem M. longissimus dorsimeat quality with electrical stimulation and non-electrical stimulation of cull cow. The M. longissimus dorsiwas treated by electrical stimulation (ES) and non-electrical stimulation (NES) after excised within30min.Analysis and compared the changes of pH and glycogen in rigor mortem and MFI, shear force, drip loss,cooking loss, color in storage between the different method. The result indicated ES had lower pH andglycogen than at1h,3h,9h significantly. Further more, ES can accelerate the increase of MFI and reduce theshear force compared with NES during storage. Drip loss and cooking loss had no significant difference. Theresult of this study showed ES can accelerate the depletion of glycogen. It can reduce the probability ofoccurrence of cold shorting and promote the MFI. Thus improve the tenderness of the meat.