Quality changes of farmed cobia steaks held in cold stores (-18 °C)

Cobia (Rachycentron canadum) steaks held in cold store (-18 degrees C) were analysed aseptically in triplicates for the sensory, total aerobic bacterial count, proximate composition, pH, thiobarbituric acid-reactive substance (TBA-RS), formaldehyde, total volatile base nitrogen (TVB-N), trimethyl amine-nitrogen (TMA-N), salt soluble nitrogen (SSN), nonprotein nitrogen (NPN), sodium dodecyl sulphate-poly acrylamide gel electrophoresis (SDS-PAGE) pattern. Steaks were sensorially acceptable up to 5 months of storage and the total bacterial counts did not exceed 6 log CFU counts. There were no significant changes in the pH values. TBA-RS values increased significantly (P < 0.05) and reached 7.34 mg of malonaldehyde kg-1 fat at the end. Formaldehyde content remained constant upto 4th month and later increased to 2.06 mu g g-1 (P < 0.05). TVB-N and TMA-N values did not exceed the acceptable limits. NPN contents showed no change, while SSN contents increased to 1.24% after 5 months. SDS-PAGE pattern indicated no protein denaturation in the fish tissue. Results indicated that TBA-RS value can only be considered as the valuable indicator in determining the quality of fish steaks held in cold stores.