CHEMICAL AND SENSORY EVALUATION OF FILLETS FROM ATLANTIC SALMON (SALMO-SALAR) FED 3 LEVELS OF N-3 POLYUNSATURATED FATTY-ACIDS AT 2 LEVELS OF VITAMIN-E

Atlantic salmon (Salmo salar) were fed three dietary levels of n-3 polyunsaturated fatty acids (PUFA) (1.0, 2.5 and 5.0% of the diets at 17% feed lipid level), each with two levels of vitamin E supplementation (0 and 300 mg alpha-tocopherol acetate/kg diet). The varying dietary n-3 PUFA contents were achieved by using soybean oil, capelin oil and sardine oil, respectively. Sensory evaluation of cooked fillet from fresh, 4-days frozen, 5-weeks frozen (-18-degrees-C) and traditionally smoked fresh fish was performed. Fillet proximate composition did not differ between high-quality cultured and wild Atlantic salmon. The total lipid fatty acid composition and vitamin-E content of the fillets were highly influenced by the fish diets. The vitamin-E content of the fillets did not influence the fatty acid composition. Significant differences were found for 7 of 14 sensory parameters when comparing for homogeneity between the dietary groups. Rancid flavour was significantly higher in fish raised on a high n-3 PUFA and low vitamin-E diet. The results indicated a combined effect according to vitamin E and n-3 PUFA contents. Coloration of the fillet seemed to depend upon lipid quality and vitamin E, in addition to the feed content of pigments. The differences in fatty acid composition of the fillets caused differences in the sensory perception of fattiness, juiciness and taste intensity. Twelve of the sensory parameters showed significant differences between treatments. The freshly sampled fish was most white, tasted less intense, was most juicy and least firm. The smoked fish showed most coloration, least taste of soya, herring, rancidity and off-flavour, probably as a masking effect of the smoking procedure. Several sensory parameters were affected by freezing and storage, including decreased whiteness and increased colour strength, taste intensity, rancid flavour and off-flavour.