Stability of Krill Meal,Astaxanthin, and Canthaxanthin Color in Cultured Rainbow Trout (Oncorthynchus mykiss) Fillets During Frozen Storage and Cooking

Rainbow trout were pigmented with diets containing synthetic astaxanthin, canthaxanthin, or dried krill meal to 6 mg carotenoid/Kg (wwb) flesh. Vacuum packaged frozen fillets were held at -18°C, -28°C or -80°C for 90 d, 180 d, or 90 d, thawed, and refrozen for an additional 90 d. Tristimulus color (L*,a*,b*), carotenoid concentration, fatty acid composition and TBARS were measured for raw and cooked fillets. We observed no change in pigment content or in a* values after 180 d frozen storage or following a thaw/refreeze cycle compared to fresh fish, even though a higher a* values were seen in fillets from fish fed synthetic astaxanthin or canthaxanthin after 90 d frozen storage suggesting that care should be used when interpreting tristimulus color values for grading programs.