Effects of Processing on Nickel Content and its Relationship with Proximate Composition in dead fresh and canned tuna fish in Iran

Background: The presence of toxic metals in food can be a risk to food safety and public health. Methods: The Iranian canned tuna was analyzed for nickel level after wet digestion with acids using Graphite Furnace Atomic Absorption Spectrometry (GFAAS). Results: The average concentration of nickel in canned and dead fresh fish found 4.20 ppb and 1.64 ppb. A significant difference in nickel level was observed between canned and dead fresh fish samples in this study. Although the concentration of nickel per g in the fillet after processing was relatively low, but the total amount of nickel in the sample shown change (256.01%). The results in present study showed the protein content in the canned fish increased to 13.17%. The moisture content in the processed fish decreased to 8.80%. The fat content in the canned fish increased to 12.86%. Conclusion: Although the protein and moisture contents significantly increased and decreased respectively after processing, but none of these factors were related to the change in nickel concentration. It may be recommended to regularly monitor the concentration of nickel metal in aquatic food products, so that human health was not at risk.