2. Nitrites & Nitrates
Some foods, especially meats, are susceptible to contamination by the bacteria that cause botulism. Nitrite and nitrates are added to the cures for these foods to make them safe form botulism infection. Sodium nitrite (NaNO2) is the most important of these chemicals. Even in the very small quantities in which it is used, sodium nitrite has strong preservative powers. In addition, it keeps meats red or pink, which products like cured ham, corned beef, and certain sausages have their characteristic color.
Nitrites gradually break down inside the cured foods, but by the time they lose their effectiveness, the curing and, in some cases, smoking procedures are finished, the food is cooked or refrigerated, and the food remains safe. However, when the food is raw and air-dried, as in the case prosciutto and carious salamis, a stronger chemical, sodium nitrate (NaNO3) is used. Nitrates break down more slowly than nitrites and therefore are effective for a longer time. (Potassium nitrate, or saltpeter, is sometime used in cures, but it is not as safe and is strongly regulated. It should be avoided.)