Effects of canning on total mercury, protein, lipid, and moisture content in troll-caught albacore tuna (Thunnus alalunga)

Fifty-six cans containing meat from either the dorsal loin or the ventral flap of 10 troll-caught albacore tuna were tested for total mercury concentration prior to and after canning and retort cooking. The albacore tuna were harvested off the US Pacific Coast during the 2004 season and weighed between 5.4 and 10.2 kg. Tuna meat was packed in cans raw or in water or olive oil, and cans were drained before post-canning analysis. The average concentrations of total mercury were: 0.17 ppm (range 0.09–0.24 ppm) in the pre-canned samples and 0.21 ppm (range 0.10–0.33 ppm) in the post-canned samples. Although the mercury concentration per gram of tissue was significantly higher following canning, the overall amount of mercury in the samples did not change significantly.