Chemistry and utilization of plankton. III. Pigmentation of cultured yellowtail with krill oil.

Abstract

The sole feeding of a formulated feed to yellowtail Seriola quinqueradiata induces poor dark grey color at the back and sides unlike the natural one of iridescent blue-green. The characteri-stic yellow band near the lateral line does not appear either. These color changes, however, were able to be improved by annexing to the formulated feed up to 2% of an oil extracted from the meal of the Antarctic krill Euphausia surperba. The krill oil contained 108mg/100g of carotenoids, which were composed of astaxanthin diester and astaxanthin monoester, 71% and 20%, respectively. The analysis of the integuments of the pigmented yellowtails revealed that carotenoid contents were 0.64-1.21mg/100g with the composition of tunaxanthin fraction, 3<-epilutein, zeaxanthin, β- carotene triol, diatoxanthin, cynthiaxanthin, and lutein in 43%-53%, 17%-28%, 9%-15%, 7%-11%, 3%-9%, <5%, and traces, respectively. This may be the first finding which showed the possibility that animals could metabolize astaxanthin to tunaxanthin.