Carbon Monoxide Used to Preserve Color
Carbon monoxide (CO) (aka tasteless smoke, filtered wood smoke, CO treated) is used to preserve the color of fish. Normally fresh fish when exposed to the air, will lose its color, and turn brownish over a period of a few days. However, the same piece of fish when treated with CO retains a fresh-looking appearance indefinitely, even after it begins to deteriorate. A 3-week-old fish that has been carbon monoxide treated will appear to be the same as a 3-day old fish.
CO Treatment not Allowed in Japan or EU
CO treatment of fish is not allowed in Japan or the EU however in July 2004 the US FDA approved CO treatments under a petition procedure known as “Generally Recognized As Safe” (GRAS). Under GRAS the FDA relies on the claims of the petitioners and does not carry out an independent safety investigation. The FDA does not consider CO a color additive but a color stabilizer making GRAS acceptable.
Modified Atmosphere Packing (MAP)
Carbon monoxide replaces the air during packing in a process known as Modified Atmosphere Packing (MAP). The concern is that if the packaged fish has been mishandled it is impossible to visually detect if it is spoiled as the CO treatment preserves the appearance of freshness.
Sources
Food Navigator USA, 2005/11/17, “FDA asked to rescind use of carbon monoxide for meats”
Modified Air Packaging www.modifiedatmospherepackaging.com/
National Institute of Health, 2018/02 Monoxide in Meat and Fish Packaging: Advantages and Limits
American Meat Institute, Carbon Monoxide in Meat Packing: Myths and Facts