Heavy metals and fatty acid composition in the viscera of different fish species

This study characterized the fatty acid profiles and concentrations of total arsenic (As), total mercury (Hg), cadmium (Cd), and lead (Pb) in visceral by-products from ten commercially important marine fish species representing eleven sample groups, including wild and cultured European seabass. The highest eicosapentaenoic acid (EPA) proportions were observed in Sardina pilchardus (8.75%), Scomber japonicus (8.18%), and Engraulis encrasicolus (8.09%), whereas docosahexaenoic acid (DHA) was highest in S. japonicus (24.36%), E. encrasicolus (20.43%), Scorpaena porcus (20.38%), and S. pilchardus (20.24%). Element concentrations ranged from 0.802 to 7.852 mg/kg for total As, 0.006 to 0.127 mg/kg for total Hg, 0.002 to 0.313 mg/kg for Cd, and 0.007 to 0.247 mg/kg for Pb. For each fish group, the available visceral material was analyzed as a bulk mixed-viscera sample, and analytical determinations were conducted in triplicate; these triplicates represent analytical rather than independent biological replicates. Several visceral samples contained high relative proportions of EPA and DHA within the total fatty acid methyl ester (FAME) profile, indicating compositional potential for further lipid-recovery studies. However, total lipid yield, contaminant speciation, batch-to-batch variability, and matrix-specific safety considerations require further evaluation before food or nutraceutical applications can be considered.