Effects of stocking density on colour characteristics and deposition of carotenoids in cultured Arctic charr ( Salvelinus alpinus)

Abstract

The colour characteristics and deposition of canthaxanthin in cultured Arctic charr ( Salvelinus alpinus), stocked at 40, 50 and 75 kg/m 3, were studied. Hunter L, a, b values of fillets, as such, or in the homogenized tissues, and skin of fish varied significantly among density groups. For belly skin, the numerical values of Hunter colour parameters decreased with increasing stocking density. However, no correlation existed between the total carotenoid contents of fish skin and their Hunter L, a, b values. On the other hand, the Hunter L values of fillets and homogenized tissues were inversely correlated with their carotenoid contents ( r = −0.9245 to −0.9844), whereas their Hunter a and b values were directly correlated with carotenoid contents ( r = 0.9040 to 0.9824 for a and 0.9527 to 0.9924 for b). The content of carotenoids in fillets of charr generally increased with duration of feeding on a pigmented diet, but a decrease was noted in some cases after 16 weeks of experimentation. However, no correlation existed between stocking density and the content of fillet carotenoids ( r = −0.6034). Canthaxanthin, echinenone, 4′-hydroxyechinenone and lutein were identified in fish fillet and canthaxanthin was the main carotenoid present.