Potassium Nitrate (Saltpetre)
What it does
Curing agent for meats.
How it's made
Mined or manufactured.
Potassium nitrate, historically known as saltpetre, is a traditional curing agent used in some dry-cured and fermented meats and certain cheeses. Like sodium nitrate it acts as a slow-release source of nitrite, which bacteria generate from it over time to preserve the meat and maintain its colour.
It occurs naturally and was once collected from mineral deposits, but food-grade material is now produced industrially, for example by neutralising nitric acid with a potassium base, or by reacting potassium chloride with a nitrate source, followed by purification and crystallisation.
The salt is crystallised into a white powder. It has a long history in traditional curing, where its gradual conversion to nitrite suits slowly matured products; its use is regulated and limited, and as with the other curing salts, only the minimum amount needed for safety is used.
Possible reactions
Converts to nitrite; nitrosamine and processed-meat concerns.