IMPACT OF FREEZING TEMPERATURE ON QUALITY OF FARMED ATLANTIC COD (GADUS MORHUA L.)

Abstract

ABSTRACT This study evaluates the impact of freezing temperature (−10,−25,−40,−55 or−70C) on thaw exudates, liquid leakage during freeze‐chilling, appearance, gaping and mechanical properties of farmed Atlantic cod fillets. Freezing temperature significantly influenced each of the characteristics studied. High temperatures (−10 and−25C) gave increased thaw exudates, and freezing at−10C gave the highest liquid leakage during freeze‐chilling. Fillets frozen at−10C had the lowest gaping and the whitest appearance. The results indicated the highest degree of toughening upon freezing at−10 or−55C, whereas the degree of toughening appeared to be similar and lower for fillets frozen at−25,−40 or−70C. The impact of freezing temperatures on the quality of farmed cod therefore appeared to be complex, but no overall beneficial effects were found by decreasing the freezing temperature below−40C.PRACTICAL APPLICATIONSFor the fish processing industry, it is important to define optimal freezing and frozen storage regimes that are cost efficient and at the same time preserve the fresh fillet quality. Farmed cod differ from their wild counterparts by having lower water content, lower muscle pH and thicker fillets. Hence, industrial guidelines for wild cod may not be transferable to farmed cod. This study showed no beneficial effects by decreasing the freezing temperature below −40C. Freezing and frozen storage are usually separated commercially. Results from the present study give valuable contribution to future studies aiming at defining optimal combination of freezing and frozen storage temperatures for farmed Atlantic cod.