Sulfites in foods: Uses, analytical methods, residues, fate, exposure assessment, metabolism, toxicity, and hypersensitivity

Sulfiting agents have a long history of use as food ingredients. Sulfur dioxide and several forms of inorganic sulfites, which liberate sulfur dioxide under the conditions of use, are food additives, collectively known as sulfiting agents. In addition to their use as food additives, the sulfites can also occur naturally in foods. Foods contain a variety of sulfur-containing compounds, including the sulfur amino acids, sulfates, sulfites, and sulfides. The key to the understanding of sulfite toxicity may lie in elucidation of sulfite metabolism. Several researchers have proposed that defects in sulfite metabolism among certain segments of the human population may put them at greater risk to the possible toxic effects of sulfite ingestion. If the current generally recognized as safe (GRAS) review leads to some limitation on the continued use of sulfites, it will be necessary to consider alternatives. Enzymatic browning will be inhibited by any process that destroys or inactivates the enzyme. Blanching would obviously work but is impractical for using on fresh fruits and vegetables. Despite their long history of use as food additives, much remains to be learned about sulfites, which would be helpful to the present concerns about their safety.