In fresh fish, the balance between the prooxidative and antioxidative factors, which control oxidative reactions, is maintained by numerous systems with prolonged storage time the control of oxidation is lost and the onset of lipid oxidation can no longer be prevented. Therefore, the enzymatic antioxidant activities (superoxide dismutase, catalase, glutathione reductase, Nitric oxide) and lipid peroxidation were determined in muscle tissues of farmed fish including (Common Carp, Mugil Cephalus and Tilapia) during freezing storage for 48 hours. The obtained results revealed that the mean values of Superoxide dismutase, reduced glutathione, catalase and total antioxidant capacity were decrease during freezing storage for 48 hours while Malonaldehyde and Nitric oxide were significantly increased during freezing storage. The relative concentration of antioxidants varies with the fish species as well as the type of fish muscle tissue. The present study concluded that freezing treatment had a great impact on antioxidant system regardless the duration of freezing storage. Therefore, control of lipid oxidation in fish involves utilizing processing and storage techniques that do not greatly decrease the activity of antioxidants enzymes.
Key words: Keywords: Farmed fish, MDA, Nitric oxide, Catalase, SOD, GSH
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