Trace elements in crayfish: regional differences and changes induced by cooking

The concentrations of Pb, Cd, Zn, Cu, Ni, Cr, Mn, Co, As, and Se were determined in the abdominal muscle and hepatopancreas from raw and cooked crayfish of Astacus astacus (L.) and Pacifastacus leniusculus (Dana), both of Swedish origin. After cooking, the concentrations of Cd, Ni, and Co in the hepatopancreas showed a decrease and the concentrations of Pb, Cu, and Mn in the abdominal muscle showed an increase. Metal and metalloid concentrations were also determined in the abdominal muscle and hepatopancreas of commercially caught and cooked crayfish, including Astacus leptodactylus (Esch.) and Procambarus clarkii (Girard), from China, Spain, Sweden, Turkey, and USA. Most of the elements showed little variation except for cadmium in the abdominal muscle of P. leniusculus from California, which was markedly higher (mean = 0.082 mg/kg) than the others (mean = 0.004 mg/kg). Metal and metalloid concentrations in hepatopancreas varied greatly within as well as between countries. In the hepatopancreas from P. leniusculus from a Swedish lake the manganese concentrations were markedly higher than in any other crayfish. The intake of cadmium from crayfish inhabiting uncontaminated waters will be low if the hepatopancreas is not consumed.