Relationships between carotenoid concentration and colour of fillets of Arctic chair,Salvelinus alpinus(L.), fed astaxanthin

The relationships between fillet colour (CIE L* a* b* and CIE L* C* H°ab) and carotenoid concentration were investigated using samples taken from Arctic charr, Salvelinus alpinus (L.), of different ages and sizes, which were held under a variety of rearing conditions. Relationships between colour parameters and carotenoid concentrations were nonlinear. Increasing carotenoid concentrations led to increased redness (a*), yellowness (b*) and chroma (C*), and decreased lightness (L*) and hue angle (H°ab). Redness was the colour parameter most highly correlated with carotenoid concentration of the Arctic charr fillets. For a given redness value, yellowness was higher in sexually mature than in immature Arctic charr. This was possibly a result of mature fish having higher proportions of idoxanthin in the fillet than immatures. Alternatively, the differences in yellowness may have been a consequence of differences in proximate composition of fillets of mature and immature charr. There were also differences in yellowness in fillets from Svalbard and Hammerfest charr, Svalbard fish having the most yellow fillets. Fish from the two strains did not differ in relative proportions of fillet carotenoids, indicating that differences in colour were mediated through differences in other chemical properties.