Potassium nitrite should never be confused with potassium chloride or other potassium-containing compounds used as dietary supplements. Unlike these compounds, potassium nitrite has specialized uses in industry and food preparation. Although classified as "generally recognized as safe" by the FDA, it continues to raise concerns because it is linked to the more dangerous nitrosamine.
Chemistry
With a single potassium atom, one nitrogen atom and two oxygen atoms, potassium nitrite has a molecular weight of 85.1. This white-to-yellow powder is so hygroscopic that it absorbs water vapor from the air. Like other hygroscopic substances, it is soluble in water, as well as in alcohol and ammonia. Once dissolved, potassium nitrite dissociates into a positively charged potassium ion and a negatively charged nitrite moiety.
Oxidizer
Like all nitrites, potassium nitrite is an oxidizer. This means that it reacts with other materials to give off oxygen. Oxidizers are hazardous because the release of oxygen encourages the combustion of other materials. Potassium nitrite is not combustible, but it accelerates the burning of combustible materials. The Department of Transportation requires that warning placards be affixed to trucks carrying this chemical.
Uses
Potassium nitrite is used in washing with hot potash to remove carbon dioxide from gas streams. It is used in the manufacture of yellow pigments and drugs, as well as in bromine recovery, tungsten dissolution and other chemical processes.
Like sodium nitrite, potassium nitrite is used to cure meats. Not only does it prevent botulism, it maintains the pink color in hot dogs, bacon, salmon, potted meat, sausages and other processed meats, by reacting with the myoglobin in the meat. Sodium nitrite is more commonly used than potassium nitrite.
Nitrosamines
Both sodium and potassium nitrites combine with proteins in meat to form nitrosoamines. Nitrosamines are potent carcinogens in animals. Their formation is blocked by adding ascorbic acid to meats. U.S. law requires producers of cured meat to add 550 ppm of ascorbic acid to their products to prevent nitrosamine formation. The Linus Pauling Institute reports that manufacturers often use erythorbic acid, which is an optical isomer of ascorbic acid.
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