Aluminium levels of fish fillets baked and grilled in aluminium foil

Abstract

During storage and preparation of food, aluminium foil is often used for wrapping heat-sensitive raw food for protection against direct heat, e.g. grilled or baked fish fillets. In this investigation the aluminium contents of grilled and baked fish fillets with and without ingredients wrapped in aluminium foil were determined. The selected fish species were mackerel (Scomber scombrus L.), a fatty species, ocean perch (Sebastes spp.), a medium fatty species, and cod (Gadus morhua) and saithe (Pollachius virens), two lean fish species. The wrapped fillets were baked for approximately 20 min at 200°C in an oven, either without ingredients or, alternatively, with vinegar and sodium chloride added. In another experiment one part of a fillet was grilled over charcoal without ingredients and the other part was grilled with onion rings and mixed spices added. All aluminium concentrations of both baked and grilled fillets wrapped in aluminium foil increased during heating. The increase in aluminium concentration ranged from a factor of 2 (baked saithe fillets without ingredients from 0.10 up to 0.21 mg/kg) to a factor of 68 (grilled mackerel fillets with ingredients from 0.07 up to 5.04 mg/kg). The aluminium contents of grilled fillets were higher than those of baked fillets. Presumably two factors were responsible for the higher aluminium contents in grilled fillets: first the higher temperature of preparation when grilling fillets and second the high aluminium content of mixed spices (63.5 mg Al/kg), which may be taken up in part by the grilled fillets. All results clearly showed that some aluminium migrated from the aluminium foil into the food. The aluminium migration seems to depend on several factors, e.g. the duration and the temperature of heating, the composition and the pH-value of food, the presence of any other substances (such as organic acids and salt) and complexing reactions that result in dissolution of the complexed metal. Considering the present state of knowledge and the suggested provisional tolerable daily intake of 1 mg Al/kg bodyweight per day of the [World Health Organisation, 1989], no risk to health of the consumer would to be expected from eating meals prepared in aluminium foil.