Sodium Nitrate
What it does
Curing agent.
How it's made
Mined or synthesised.
Sodium nitrate acts as a slow-release curing preservative in some cured and fermented meats and in certain cheeses. It works as a reservoir: bacteria gradually convert it to nitrite, which is the substance that actually prevents dangerous bacterial growth and fixes colour, making it useful for products cured slowly over a long time.
It occurs naturally as a mineral (Chile saltpetre) and was historically mined, but food-grade sodium nitrate is now generally made industrially, for example by neutralising nitric acid with a sodium base such as sodium carbonate or sodium hydroxide, then purifying and crystallising it.
The salt is crystallised into a white powder. Its use is regulated with strict limits, and it is chosen for traditional long-cured products where a gradual, sustained supply of nitrite is needed rather than the immediate action of nitrite salts; like nitrites, it is used at the minimum effective level.
Possible reactions
Converts to nitrite; similar concerns.