Proximate composition via moisture, crude fat, crude protein,
and ash were analyzed using AOAC (2000) methods. Thiobarbutiric
acid (TBA) value was determined spectrophotometrically
(Tarladgis and others 1960) to evaluate oxidation stability and the
results were expressed as TBA value, mg malonaldehyde per kilogram
of fish. Peroxide value (PV) at each sampling day was analyzed
iodometrically (AOCS 1999) and free fatty acid (FFA) value by
themethod of Link (1959). Tri methylamine nitrogen (TMA-N) and
total volatile base nitrogen (TVB-N) were estimated by Conway’s
(1950) microdiffusion method. ATP breakdown products were analyzed
using high-pressure liquid chromatography (HPLC) (Ryder
1985). Quantification was made by external standard method and
K-value was calculated as a ratio of the sum of hypoxanthine and
inosine to total amount of ATP related compounds as defined by
Saito and others (1959). The biogenic amines content in fish was
determined using HPLC by pre column derivetization with benzoyl
chloride (2% solution in acetonitrile) (Merck and Co. Inc., N.J.,
U.S.A.) as described by Redmond and Tseng (1979), with modification
in gradient elution system as per the method of Ozogul
and others (2002) using acetonitrile and water. Total plate count
was carried out by the method of Hitching and others (1995) using
spread platemethod