Saltpeter
What is saltpeter?
Potassium nitrate is a chemical compound with the chemical formula KNO3. It is an ionic salt of potassium ions K+ and nitrate ions NO3−.
It occurs as a mineral niter and is a natural solid source of nitrogen. Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpeter or saltpetre.
Major uses of potassium nitrate are in fertilizers, tree stump removal, rocket propellants and fireworks. It is one of the major constituents of gunpowder (blackpowder) and has been used since the Middle Ages as a food preservative.
Food preservation
In the process of food preservation, potassium nitrate has been a common ingredient of salted meat since the Middle Ages, but its use has been mostly discontinued because of inconsistent results compared to more modern nitrate and nitrite compounds. Even so, saltpeter is still used in some food applications, such as charcuterie and the brine used to make corned beef. When used as a food additive in the European Union, the compound is referred to as E252; it is also approved for use as a food additive in the USA and Australia and New Zealand (where it is listed under its INS number 252). Although nitrate salts have been suspected of producing the carcinogen nitrosamine, both sodium and potassium nitrates and nitrites have been added to meats in the US since 1925, and nitrates and nitrites have not been removed from preserved meat products because nitrite and nitrate inhibits the germination of C. botulinum endospores, and thus prevents botulism from bacterial toxin that may otherwise be produced in certain preserved meat products.
Food preparation
In West African cuisine, potassium nitrate (salt petre) is widely used as a thickening agent in soups and stews such as Okra soup and Isi ewu. It is also used to soften food and reduce cooking time when boiling beans and tough meat. Salt petre is also an essential ingredient in making special porridges such as kunun kanwa literally translated from the Hausa language as 'salt petre porridge'.