Distribution of hazardous and essential elements in protein fractions of raw and processed tuna (Euthynnus affinis) and associated health risks for coastal populations

Trace elements (TEs) in the marine environment can bioaccumulate in seafood, posing risks to ecosystem integrity and human health. This study investigated 12 TEs in raw and processed Euthynnus affinis protein fractions. Fifty samples (N = 50) were collected and subjected to various processing methods (n = 10), including raw, washing, cold-blanching, boiling, and frying. Muscle proteins were separated into five fractions: myofibrillar (MP), sarcoplasmic (SP), alkali-soluble (AP), acid-soluble (ADP), and residual proteins (RP), and subjected to ICP-MS analysis showed Zn and Fe were most abundant in raw tuna and its fractions. Raw tuna contained higher levels of Hg (31.3 μg/kg), Cd (6.20 μg/kg), As (186 μg/kg), and Pb (80.8 μg/kg) than pre- and thermally processed tuna and their fractions. Washing reduced Cd and Pb levels in SP from 6.12 to 2.43 μg/kg and from 41.3 to 15.6 μg/kg, respectively. Cold blanching further lowered Pb and Hg levels to 13.9 μg/kg and 4.79 μg/kg, respectively, while boiling eliminated Hg in ADP. Cd, Hg, and Pb in the raw and processed tuna were below the MRL stipulated by the EC and FSSAI. The weekly intake of all analyzed TEs was within the safe limits established by the regulatory authorities. Health risk indicators, including the target hazard quotient (THQ), total THQ, and lifetime cancer risk remained within the safety margins for all treatments. Multivariate analysis revealed clustering between toxic and essential TEs, with processing methods affecting the metal distribution. Boiling and cold blanching effectively reduce toxic TE exposure, emphasizing the importance of cooking for seafood safety.