Sodium Nitrate also called Chile saltpeter (to differentiate from other saltpeter (potassium nitrate), has antimicrobial properties used as a food additive for long-term curing.
Sodium nitrate is converted into Sodium Nitrite by microorganisms present on the meat prevent botulism germ or butyric acid bacteria poisoning & provides the characteristic flavor and red color fixative in cheese, cured meats and pickled fish.
Home curing should not exceed 0.1g per 500g of meat