Pigmentation of cultured red sea bream with astaxanthin diester purified from krill oil.

The pigmentation of cultured red sea bream Pagrus major with the Antarctic krill Euphausia superba is known to be attained by feeding any of the frozen krill, krill meal, and oil extracted from the meal. This suggests that astaxanthin diester (I), which is the common main carotenoid in those krill products, should be effective, but there is no evidence. Accordingly, an attempt was made to prove it. I purified from krill oil was added to a formulated feed at concentrations of 0.12-12.8mg astaxanthin/100g diet and the feeding experiment was conducted for 8 weeks. I was found very effective, being superior to frozen krill and krill oil. The analysis of the integuments of the pigmented fish showed that carotenoid contents were 0.46-1.72mg/ 100g and that the composition in fish receiving I at a level of 12.8mg astaxanthin/100g diet was I (53%), astaxanthin monoester (4%), and esterified yellow carotenoids such as tunaxanthin fraction (22%), 3'-epilutein (9%), lutein (trace), zeaxanthin (5%), diatoxanthin+cynthiaxanthin (2%), and β-carotene triol (4%). This indicates that a part of I ingested by red sea bream should have been metabolized to tunaxanthin via β-carotene triol, zeaxanthin, and 3'-epilutein.