Arsenolipids in salmon are partly converted to thioxo analogs during cooking

Background: Arsenic hydrocarbons, major arsenolipids occurring naturally in marine fish, have substantial cytotoxicity leading to human health-related studies of their distribution and abundance in foods. These studies have all investigated fresh foods; because most fish are cooked before being consumed, it is both food-and health-relevant to determine the arsenolipids present in cooked fish. Methods: We used HPLC/mass spectrometry to investigate the arsenolipids present in salmon (Salmo salar) before and after cooking by either baking or steaming. Results: In raw salmon (total As 2.74 mg kg-1 dry mass, of which 6% was lipid-soluble), major arsenolipids were three arsenic hydrocarbons (oxo-AsHC 332, oxo-AsHC 360, and oxo-AsHC 404, ca 55% of total arsenolipids) and a band of unidentified less-polar arsenolipids (ca 40%), trace amounts of another four arsenic hydrocarbons and two thioxo analogs were also detected. During the cooking process, 28% of the oxo-AsHCs were converted to their thioxo analogs. Conclusion: Our study shows that arsenic hydrocarbons naturally present in fresh fish are partly converted to their thioxo analogs during cooking by either baking or steaming. The greater lipophilicity of the thioxo analogs could alter the mode of toxicity of arsenic hydrocarbons, and hence future food regulations for arsenic should consider the influence of cooking on the precise type of arsenolipid in fish.

Automated summary

This study investigated the arsenolipids present in salmon before and after cooking, finding that a significant portion of arsenic hydrocarbons naturally present in fresh fish are converted to their thioxo analogs during the cooking process. This conversion may influence the toxicity of the compounds and suggests that future food regulations for arsenic should consider the impact of cooking on the type of arsenolipid in fish.