The Impact of Various Types of Cooking on the Fate of Hg and Se in Predatory Fish Species.

This study addresses the effect of various cooking approaches on total Hg (Hg) and total Se (Se) contents in three predatory fish species. For this purpose, samples of swordfish, dogfish, and tuna from regular French (fish) markets were cooked by boiling, steaming, grilling, and frying, respectively. The levels of Hg and Se in raw and cooked samples were determined by inductively coupled plasma-mass spectrometry. The data showed a significant increase in Hg and Se levels between raw and cooked samples (33% of the samples for Se and 67% for Hg) due to the water loss during the cooking. High intra-species variation related to Hg and Se levels was found. Considering the level of exposure to Hg through fish consumption and taking also into account the possible protective effect of Se (expressed here via the Se/Hg molar ratio), the safest cooking approach corresponds to grilled swordfish, fried tuna, and steamed dogfish, which show Se/Hg molar ratios of (1.0 ± 0.5), (4.3 ± 4.2), and (1.0 ± 0.6), respectively.