Principles of Curing

Curing of meat involves the addition of nitrite and/or nitrate salts together with sodium chloride. The effective compound is nitrite or its derivatives. Nitrate becomes an active curing agent only after reduction to nitrite, which is key in the labeling of natural cure products. The usual pH range of meat during meat processing is 5.0–6.5; under such conditions, nitrite forms nitric oxide (NO), which binds to myoglobin. The NO–myoglobin or NO–heme pigment is heat stable and bestows a red curing color to the meat. In the meat matrix, nitrite is also oxidized to nitrate and acts as an oxygen scavenger or as an antioxidative compound. By this and other complex chemical reactions with biomolecules, the concentration of nitrite is reduced to less than half of its ingoing quantity in a ready-to-eat meat product. During storage, the concentration of nitrite is further reduced. Due to the very low levels of secondary amines in fresh meat, the low ingoing nitrite concentration, and the relatively high pH value, cooked meat products do not form carcinogenic N-nitrosamines upon thermal processing. On the other hand, raw long-aged meat products may contain traces of various N-nitrosamines