Thermal Reduction of Bioaccumulated Mercury in Thunnus albacares: Systematic Mechanisms and Health Risk Mitigation

Mercury (Hg) bioaccumulation and biomagnification in the marine food chain pose significant health risks, particularly from consuming apex predators like yellowfin tuna (Thunnus albacares). Selenium (Se) can mitigate Hg's toxicity by binding to yellowfin tuna. Although the Hg content of raw tuna is well documented, the impacts of thermal treatment on the mechanism and risk mitigation remain underexplored. This study investigated the effects of thermal processing on Hg levels in yellowfin tuna and assessed the changes in the health risk indicators. The results demonstrated a significant average reduction of 28% in total Hg (THg), accompanied by a 31% decrease in hazard quotient (HQ) values and an 80% increase in the selenium-to-mercury molar ratio (Se/Hg). Thermal exposure at 180 °C for 20 min resulted in up to a 71% reduction in THg. Mechanistic analysis confirmed volatilization as the primary mechanism for Hg reduction, with over 95% of Hg released in the elemental form (Hg⁰).