Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2007
Publication Date: 12/1/2007
Citation: Li, M.H., Robinson, E.H., Oberle, D.F., Zimba, P.V. 2007. Effects of Various Dietary Carotenoid Pigments on Fillet Appearance and Pigment Absorption in Channel Catfish Ictalarus punctatus. Journal of the World Aquaculture Society 38:557-563. Interpretive Summary: Consumers prefer fish fillets having a neutral or white appearance. Occasionally, fish are processed that contain a yellow color. Experiments were conducted to identify the source of this yellow color. Fish were fed several representative pigments found in different algal classes. A pigment found in cyanobacteria was found to be accumulated in fillet tissue. The presence of cyanobacteria, coupled with fish consumption of these algae, would contribute to yellow fillets. These fillets would contain anti-oxidant compounds of nutritional benefit to consumers.
Technical Abstract: A study was conducted to evaluate effects of various carotenoids on skin and fillet coloration and fillet carotenoid concentration in channel catfish Ictalurus punctatus. For 12 weeks, juvenile catfish were fed one of six experimental diets containing no supplemental carotenoid or 100 mg/kg of one of following carotenoid additions: ß-carotene, lutein, zeaxanthin, canthaxanthin, and astaxanthin. Visual yellow color intensity score was highest for fish fed lutein, followed by zeaxanthin, astaxanthin and canthaxanthin, and lowest for fish fed basal and ß-carotene diets. Skin and tissue Commission Internationale de I’Eclairage (CIE) yellowness value was the highest in fish fed lutein, followed by fish fed zeaxanthin and astaxanthin, canthaxanthin, and lowest for fish fed basal and ß-carotene diets. Fish accumulated the supplemental carotenoids in muscle tissues, but concentrations of different carotenoids in the tissue varied greatly. Approximately 30% of the lutein added was converted to echineone; no conversion was observed among other supplemental carotenoids. Results from the present study indicate that channel catfish can accumulate yellow pigments lutein and zeaxanthin and red or pink pigments canthaxanthin and astaxanthin in the flesh, resulting in yellow coloration. The yellow pigment ß-carotene does not appear to deposit in skin or flesh at levels sufficient to alter the coloration.