Aluminium contents in edible parts of canned fish products during prolonged storage at room temperature

In these investigations aluminium contents of different canned fish product s stored for prolonged time periods were determinated. The aluminium determ ination of the samples documented the aluminium migration from can material into the food in correlation with time from < 1 until > 30 years. The incr ease of aluminium contents, especially in herring fillets of continue store d canned fish products, were significant. In comparison with corresponding fillets of fresh fish from the North Sea the aluminium contents of old samp les were very high and increased maximal to a factor of 3000. The aluminium increase was dependent on the duration of storage. Additionally the alumin ium migration was influenced from the composition of other ingredients and their characteristics like pH-value and water content, the quality of cans, the lacquer of cans, respectively, the conditions of manufacture and stora ge and the presence of compounds like acids and salts, because the formatio n of stabile aluminium complexes results in dissolution of the complexed me tal. The aluminium contents of different sauces of newly canned fish products (< 2 years) were higher than the contents of fillets because of the vegetable ingredients. In medium time period stored canned fish products (> 5 years) the ratio of the aluminium contents between sauces and fillets were revers ed. Probably the stronger affinity of the aluminium ion to the fillet prote ins was the main reason for this process. The aluminium contents of commercially canned fish fillets with a guarantee d shelf life of 4 years were also higher than corresponding fillets of fres h fish. But in comparison with the contents of "historic" canned fish sampl es the aluminium levels were low and resulted from the ingredients of the s auces and/or the conditions of manufacture. The average aluminium intake by humans is according to literature normally between 2 and 10 mg Al/day (GRE GER, 1985; LIUKKO-NEN-LILJA und PIEPPONEN, 1992; PENNINGTON,1987; TREIER un d KLUTHE, 1988; TREPTOW und ASKAR, 1987). The World Health Organisation (WH O 1989) suggested a provisional tolerable daily intake of 1 mg Al/kg bodywe ight per day (BECKER et at., 1990). Both values indicate that the consumpti on of commercially canned pelagic fish fillets together with their sauces f orms no health risk for humans under normally habitual consumption, taking into account that aluminium absorption by humans is usually extremely low ( between 1-3%).