Distribution of alpha-tocopherol in fillets of turbot (Scophthalmus maximus) and Atlantic halibut (Hippoglossus hippoglossus), following dietary alpha-tocopheryl acetate supplementation

Abstract

The present study investigated the distribution of α-tocopherol (vitamin E) in fillets of turbot (Scophthalmus maximus) and Atlantic halibut (Hippoglossus hippoglossus). Turbot and Atlantic halibut were fed commercial diets, supplemented with different levels of α-tocopheryl acetate at the dietary target levels of 100, 500 and 1000 mg α-tocopheryl acetate kg−1 diet. The actual levels were 72, 547 and 969 for turbot, while halibut received 189, 613 and 875 mg α-tocopheryl acetate kg−1 diet. Turbot were fed the diets for 24 weeks, while Atlantic halibut were fed for 20 weeks prior to slaughter. At the end of the feeding periods fish had reached a final weight of around 1 kg. Fish were slaughtered and filleted. From the four fillets obtained per fish, 22 samples were taken from designated areas and analysed for their α-tocopherol content. The average concentrations of α-tocopherol incorporated in turbot and Atlantic halibut increased with increasing levels of α-tocopheryl acetate in the diet. Atlantic halibut had significantly (P < 0.05) more α-tocopherol in positions 2/II and 1/I than in position 9/IX. Turbot had significantly (P < 0.05) more α-tocopherol in position 2/II than in positions 1/I, 4/IV and 11/XI. By mapping α-tocopherol concentrations in fish fillets, a high degree of quality prediction may be established. Moreover, this study may help scientists in their choice of sampling position, when investigating if α-tocopheryl acetate supplementation resulted in successful α-tocopherol incorporation.