Flesh liquid and carotenoid composition of Scottish farmed Atlantic salmon (Salmo salar)

Samples of steaks from market-size salmon (2.5-5 kg), produced under the require ments of the Product Certification Scheme for Scottish Quality Farmed Salmon, we re obtained from five Scottish salmon producers on a weekly basis for over 2 yea rs. Samples were assayed for total lipid content, lipid class composition, fatty acid composition, vitamin E content, and carotenoid pigment [astaxanthin (AX) a nd canthaxanthin (CX)] content. In addition, samples were obtained from the same producers to assess loss of carotenoid pigment in the period up to 120 h post-h arvest and to measure lipid and pigment content of different body regions. The a nalyses showed a positive correlation between dietary lipid and deposition of li pid in flesh, although there was great variation in flesh lipid content within e ach dietary lipid level. The average lipid content of Scottish salmon was 10.1 + /- 2.9% (n = 495). Salmon flesh was rich in the n-3 highly unsaturated fatty aci ds, 22:6n-3 and 20:5n-3, with average values of 11.3 and 5.4% of total fatty aci ds or 10.2 and 4.8 g/kg flesh, respectively. Vitamin E content of salmon flesh w as around 30 mg/kg but was significantly higher in fish fed the lowest dietary l ipid level. Studies investigating changes in carotenoid pigmentation up to 120 h post-harvest suggested that fish fed AX alone showed a loss of pigment over tim e that did not occur in fish fed either CX alone or a combination of AX and CX. Measurement of lipid content of different body regions showed that the highest l evels were found in the region immediately in front of the dorsal fin and that t he lowest lipid levels were in the tail region. Total lipid content of all five body zones was positively correlated with dietary lipid. Carotenoid pigment leve ls were the same across all body zones and were not affected by dietary lipid.