Cooking–freezing–reheating (CFR) of sardine ( Sardina pilchardus) fillets. Effect of different cooking and reheating procedures on the proximate and fatty acid compositions

Abstract

The sequential cooking–freezing–reheating (CFR) method was studied. Sardine ( Sardina pilchardus Walb) fillets were cooked by frying, oven-baking or grilling, frozen, and then reheated using conventional or microwave ovens in order to study changes occurring in the proximate and fatty acid compositions. Both cooking and freezing–reheating affected ( P<0.001) the proximate composition. Frying produced the highest water loss and fat gain, followed by grilling, and then by oven-baking. Microwave oven-reheating (MR) induced higher dehydration than conventional oven-reheating (OR), with grilled–frozen–MR samples also loosing fat and ash. Frying significantly ( P<0.001) affects the fatty acid composition of sardine, increasing oleic and linoleic acids and decreasing eicosapentaenoic and docosahexaenoic acids. Oven-baking and grilling minimally affected the fatty acid content. Freezing–reheating significantly affected ( P<0.001) the fatty acid composition with the content of oleic acid increasing and those of the ω-3 fatty acids, decreasing more in MR than in OR. Thus, according to the positive effect attributed to ω-3 fatty acids, cooked samples with no further treatment would be preferred to their respective CFR counterparts. However, OR should be used instead of MR when the CFR system is performed.