Smoked fish from Gabon: nutritional benefits vs. contaminant risks

Smoked fish is the most common form of fish consumption in many African countries. Smoking is likely to cause changes in nutritional value and in the concentration of certain toxic elements. We assessed these changes in the Bonga shad (Ethmalosa fimbriata, Bowdich 1825). Fatty acids (26), vitamin A, trace elements (14) and polycyclic aromatic hydrocarbons (PAHs, 24) were examined in E. fimbriata at different smoking durations (fresh, 24 h, 48 h and 72 h). Composition of smoked fish revealed high inter-individual variability. Smoking did not affect total fatty acid concentrations, but it led to a 4.5-fold decrease in vitamin A and a decrease in the concentrations of Ca, Mg, Mn, Pb and Sr. Meanwhile, it increased the concentrations of PAHs (by a factor of 42), Cd, Mo and Na. Despite these changes, toxic metals (As, Cd and Pb) and PAHs levels remained within safety limits, except for the B(a)P Toxic Equivalent (TEQ) in 72 h-smoked fish. High inter-individual variability in toxic metals, PAHs and nutrients concentrations is suspected to originate from the heterogeneity of the smoking process, and to natural variation in fish. Overall, our results highlight the safety of artisanal smoked fish for human consumption when processed under certain conditions. To further enhance consumer safety, dietary recommendations would advise ensuring fish skin integrity in order to reduce flesh contamination.