Pink salt is a common name for a a mixture of sodium chloride, or table salt, and sodium nitrite. It is also called InstaCure, Prague Powder, and "Pökelsalz" in German. It is used on meat so that the botulinum toxin cannot be produced. Pink salt is toxic to humans but is not present in finished, cured meats in a high enough dose to cause illness or death.
Pink salt is dyed pink in color so it cannot be confused with table salt. The nitrite imparts characteristic color and flavor to cured meats.
Background - Botulism Hazard
Once known as sausage disease or sausage poisoning, botulism was named after "botulus," the Latin word for sausage. It was first described in Germany by Justinus Kerner in Wurttemberg in 1817, although the pathogen and toxin was not identified until 1895 by Emile Pierre van Ermengem, a professor at the University of Ghent. (source)
Clostridium botulinum is the name of a gram positive, obligate anaerobic (cannot grow in presence of oxygen) bacterium which is present in the soil and water. The durable spores can be airborne and can land on food. If it finds the right environment; low acid and little or no oxygen, it will grow and reproduce.
If the bacterium reproduces it can produce toxins called botulinums and cause botulism, a foodborne illness caused by ingesting the toxin.
It is difficult to kill; the spores tolerate 212°F (100°C) temperatures so heating to 240 - 250°F (120°C) for 5 - 10 minutes is necessary to destroy them. This necessitates the use of a pressure canning device when home canning.
If the bacteria is left to grow and produces the toxin which causes the illness, heating the food for 10 - 20 minutes to temperatures above 176°F (or 80°C) will destroy most of the toxin. This is a secondary step to insure your home canned, non-acidic food is safe to eat. (source)
Other ways to control the bacteria are by using acids such as vinegar in canning recipes, canning high acid fruits and vegetables, using high sugar or salt concentrations (as for jam or pickles), keeping the food at temperatures below 38°F (3°C) and using nitrites or nitrates.
Nitrites inhibit the growth of anaerobic bacteria, which logically inhibits toxin production. Nitrates turn into nitrites over time which makes them a time - release form of the inhibiting compound. Both are themselves toxic to humans in high doses. Home cooks therefore are allowed to purchase sodium nitrite which has already been cut with salt, reducing the chance of accidental overdose.
Nitrite is eventually used up in the meat during the curing process and converted to nitric oxide, which is not harmful. The amount of nitrite in cured meats is not harmful at several times normal levels of consumption (this site claims you would have to eat 14 pounds of salami at one sitting to consume a dangerous amount).
Nitrate --> Nitrite --> Nitric Oxide
Pink salt comes in two main forms, Cure #1 and Cure #2.
Cure #1 type of pink salt is used in to cure all meats that require cooking, brining, smoking, or canning. This includes poultry, fish, ham, bacon, luncheon meats, corned beef, pates and other products. It consists of 93.75% table salt and 6.25% sodium nitrite. and is used at a rate of 1 teaspoon per 5 pounds of ground meat.
If using it for a brine use 1/2 cup InstaCure No. 1 (or other name) per gallon of water, plus 1 3/4 cup table salt, 2 1/4 tablespoon sugar and any spices you wish (see sausagemaker.com for products and recipe).
Cure #2 is formulated for dry cured products such as pepperoni, hard salami, proscuitti hams, dried sausages and other products which do not require cooking, smoking or refrigeration. One level teaspoon (from a mix of 1 ounce sodium nitrite (6.25%), 0.64 ounces sodium nitrate (4%) to 1 pound of salt) is used per 5 pounds of meat.
The cures are not interchangeable so follow the recipe you use closely and use a recipe from a reliable source.
Do not use pink salt like regular table salt. Do not sprinkle it on your food.