Some foods, especially meats, are susceptible to contamination by the bacteria that cause botulism (see p. 20). Nitrites and nitrates are added to the cures for these foods to make them safe from 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 is why 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. On the other hand,when the food is raw and air-dried, as in the case of prosciutto and various 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 sometimes used in cures, but it is not as safe and is strongly regulated. It should be avoided.)
Nitrates and nitrites are the subject of controversy regarding their safety. Substances called nitrosamines form when foods containing nitrates or nitrites are sub jected to very high heat, such as when bacon is fried. Nitrosamines are known to cause cancer. Using only nitrites to cure foods usually avoids this problem because the nitrites break down quickly and are not usually a factor when the food is cooked. Nitrates, on the other hand, because they remain in meats longer, should not be used for curing bacon for this reason.
Some people feel that all use of nitrites and nitrates should be avoided because of the nitrosamine factor. However, if only nitrites and not nitrates are used in foods that will be exposed to extreme heat, the risk is low—much lower than the risk of botulism. So far,we know of no adequate substitute for these chemicals in curing pork and other meats.
Two special mixtures are employed that make it easy to add nitrites and nitrates in very low but sufficient concentration:
1. Prague Powder #1, or curing salt, is a blend of 6 percent sodium nitrite and 94 percent sodium chloride, or regular table salt. It is colored pink so that it will not be confused with regular salt, and thus it is often called tinted curing mix (TCM). It is also sold under various trade names, such as InstaCure I.
2. Prague Powder #2 is similar to Prague Powder #1 except that it contains nitrates in addition to nitrites. It is used in curing products that have a long curing and drying period, as explained above. Prague Powder #2 is not used in any of the recipes in this chapter. Air-dried cured meats require advanced procedures that are beyond the scope of this book.
Fish and seafood are usually cured without the use of nitrites. Fish is almost always cured under refrigeration and the salt cure is sufficient to protect it, even when it is cold smoked (p.828).
The quantity of nitrite to be added to meats depends on several factors, including the type of meat, the type of cure, and the length of curing time. For cooked sausage, the U.S. Department of Agriculture recommends 156 parts nitrite per million parts meat. This is equivalent to 1 ounce (30 g) nitrite per 400 pounds (192 kg) meat.To translate this to quantities similar to those used in this chapter, 10 pounds (4.5 kg) cooked sausage requires about 0.025 ounces (0.7 g) nitrite.This is the amount of nitrite contained in 0.4 ounces or 2 teaspoons (11 g or 10 mL) Prague Powder #1.
Keep in mind, however, that not all the nitrite specified in a recipe may be absorbed into the meat. In the case of the basic dry cures and brine cures (described below), part of the curing medium is discarded after the cure is complete.Therefore, enough nitrite must be used so the portion that is absorbed is adequate for the cure. The only exception is the case of sausages, in which all of the curing medium is mixed directly with the meat.The recipes in this book contain appropriate quantities of nitrite to cure the product.
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