Muscle from fresh carp

This procedure also can be used to differentiate between fresh and frozen-thawed fish. In fresh, homogenized carp muscle we found four GOT isozymes—one sarcoplasmic and three mitochondrial (48). Upon freezing of whole carp, the mitochondrial isozymes (GOTmi, GOTM2, GOTM3) are released (Table VII) (49). Thus, press juice from fresh carp muscle exhibits one band, whereas after freezing and thawing four bands appear. 

Myosins isolated from various frozen stored fish muscles had slightly lower ATPase activity than those from fresh muscles (94, 95). A decrease in ATPase activity was found also with isolated carp myosin when stored at -20°C (82) the rate of decrease was faster than with actomyosin isolated from the same fish. As with actomyosin, the decrease in ATPase activity was preceded by a temporary rise in activity M50% the pre-freezing value). 

ATPase. Myosins isolated from various frozen-stored fish muscles exhibit specific activities for ATPase that are slightly lower than the specific activities of myosin from fresh muscles (73,74). The decline of ATPase activity also occurs with myosin isolated from carp, when storage is conducted at — 20°C (64). Like carp actomyosin, the decline is preceded by a temporary rise in activity. 

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