Abstract: The objective of this study was the comparison of thermo-stability of myofibrillar ATPase in PSE- Pork and normalpork with freshwater fish muscle. When the myofibril suspending solution was stored at 35℃ for various times and at differenttemperatures for 30 minutes, the Ca2+-ATPase activity was studied. The results indicated: with the increasing of salinity ,themyofibrillar Ca2+-ATPase decreased, but when in the same salinity, Mg2+-ATPase>Ca2+-ATPase. With the increase of incubationtime and temperature, the myofibrillar Ca2+-ATPase activity decreased. However, the effect of temperature on myofibrillar Ca2+-ATPase activity was more apparent than incubation time. At 45℃, the first order rate constants(KD) of myofibrillar Ca2+-ATPaseof cold blooded animal (fish)was larger than warm blooded animal (pork). The thermo-denaturation of silver carp myofibrillarprotein was the worst while, thermo-stability of the normal pork was the best. So the myofibrillar ATPase could be used as acharacteristic parameter to distinguish the muscle species.

Key words: PSE, pork, freshwater fish, MfATPase, thermostability