Nitrate

Nitrate does not cure. It is a reservoir, and its whole role is to become nitrite. Nitrate-reducing bacteria of the meat's own flora, chiefly the staphylococci and micrococci a curesmith may add as a starter, convert it step by step to nitrite, which then does the colour-fixing and the guarding. Everything nitrate achieves, it achieves at second hand.

That indirectness is both its value and its difficulty. Because the reservoir empties slowly, a long-aged ham or salame keeps a trickle of fresh nitrite renewed across the months of its ripening, far longer than a single dose of nitrite would last, which is why nitrate belongs to the slow, cool, dry-cured products above all. But the amount of nitrite actually produced depends on the flora, the temperature and the time, none of them tightly controlled, so nitrate curing has always demanded patience and carried a margin of uncertainty that pure nitrite does not.

Historically this was the only route there was. As saltpetre, potassium nitrate cured the world's meat for some two millennia before the discovery, in the early twentieth century, that nitrite was the active agent all along. Today nitrate reaches the meat, never neat, but folded into a curing salt: into Cure #2 or the European Salvianda, or added as saltpetre for a long southern-style dry cure. It is deliberately kept out of quick and cooked products, where there is no time or flora to reduce it and no benefit to be had.

Regulation treats nitrate more gently than nitrite, since the health concern attaches mostly to nitrite and the nitrosamines that follow it. In the United States dry-cured products may carry up to 2,187 ppm of sodium nitrate, though it is banned in bacon. In the EU, under Regulation (EU) 2023/2108, nitrate limits are likewise re-expressed as the nitrate ion and governed in part by residual levels, with producers required to investigate rather than automatically discard a product that exceeds them. As always, the current figure for the product and country is the one that matters.