The effect of cooking on the content of heavy metals in fish (Tilapia nilotica)

Fish (Tilapia nilotica) were grown in polluted water with some heavy metals namely cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn). The concentrations of metals in fish water environment were 5, 10 and 15 ppm for Cd, Cu and Zn, respectively, while Pb concentrations were 20, 40 and 80 ppm. The results revealed that heavy metal contents in fish parts varied according to concentrations in the environment and the type of fish tissue. The highest levels (all examined metals) were found in visceral tissues followed by the head. The lowest value was found in fish flesh. The heavy metal content in all fish parts decreased on steaming and baking. The reduction in the metal content on baking was much greater than on steaming.