The effect of different methods on fatty acid composition of Tilapia, Oreochromis niloticus, fillets

Tilapia, a perch fish from Cichlidae family has witnessed a vast and fast growth in artificial culture due to simple and inexpensive procedures for the practice. One of the most important farm species is considered to be the Nile Tilapia (Oreochromis niloticus). The effects of different cooking methods on fatty acid composition and nutritional value of Tilapia fish fillet were evaluated. The cooking methods included: Red off, microwave, oven cooking, barbecue, boiled water and raw treatment. The protein content was assessed using the Kjeldahl method, moisture was evaluated through dry method, fat and ash through Soxhlet and electric furnace methods. To measure the composition of fatty acids, Gas-chromatography method (GC) was applied, and the Bligh and Dyer method of extraction and identification of fatty acids was implemented. The results showed that applying different curing methods caused moisture loss of 1-9%, 2-12% increase in protein content, fat reduction of 0.2-4.2% (excluding the red off treatment in which fat increased by about 0.5%), increase in ash of 0.7-0.15%, reduction of Mono Unsaturated Fatty Acids between 1-6% and increase in Poly Unsaturated Fatty Acids between 0.5-14%. The rate of saturated fatty acids showed an increase of 0.6-1.6% in all treatments with the exception of baking and red off treatments. The results indicated the lowest change (about 0.2%) in EPA, in the microwave and grilled fillet treatments and the highest change (0.7%) in the red off fillets compared to raw samples. The minimum change in DHA was observed in the oven-cooked fillets (0.45%) and the maximum change (2.5%) in the red off fillets. The highest EPA and DHA were found as 1.33 and 3.32% in samples cooked in oven. Results showed that the ratio of 6/ 3 increased in the red off samples compared to other treatments.