Curing salts are combinations of regular salt (NaCl) and nitrates. Nitrates by its nature are powerful poisons and for safety reasons are mixed with common salt (NaCl) and are known as curing salts. The most known are : Instacure #1, Instacure # 2 and some curing salts made by Morton Salt. Only in big meat processing plants will the nitrates be added directly to salt and meat in required amounts. And that of course will be done by a trained personel under strict supervision. General public buys nitrates already premixed in safe amounts and ready to apply Instacure # 1 and Instacure # 2. Both cures were known before as Prague # 1 and Prague # 2.
Sodium Nitrate (NaNO3) does not cure meat directly and initially not much happens when it is added to meat. After a while micrococci and lactobacilli bacterias which are present in meat, start to react with nitrate and create Sodium Nitrite (NaNO2) that will start the curing process. This transformation is possible only by the presence and growth of bacteria from (Micrococcaceae or Achromobacter family) and if those bacterias are not present in sufficient numbers the curing process may be inhibited.
Nitrate (NO3) bacteria
Nitrite (NO2)
Nitrate reacts with bacteria and realeases nitrite. Here we have a little dilema those bacterias are rather dormant at the recommended curing temperatures below 41º F (5º C) but the best conditions for the nitrate action are at 46
50º F (8 10º C). On the other hand those higher temperatures (46 50º F) are an open invitation to different types of bacterias that can spoil the meat or develop toxins. For those reasons to the mixture of salt and nitrate we add a little amount of sodium nitrite so we can jump start the curing process at recommended low temperatures. Once the sufficient amount of salt will penetrate the cured meat it will act as a barrier to the growth of bacterias and the curing temperatures could be higher
hams could be safely left hanging and air dryed as it was done in Spain and Italy for centuries. Now at those slightly higher temperatures, nitrate kicks into the action continuously releasing a fresh supply of nitrite. The Instacure # 2 mix has a mixture of salt, nitrate and sodium nitrite because it is used for making air dryed products. This requires prolonged times and a continuous supply of fresh nitrite which is in time released by nitrate.
Sodium Nitrite (NaNO2) in time reacts with oxygen and becomes nitric oxide (NO) which reacts with meatsÅ‚s natural colorant “myoglobin" (NO+ Mb) creating a dark red color of cured meat known as nitrosomyglobin (NOMb). When the meat is heated to 130 140º F (54
60º C), the nitrosomyglobin is converted to a stable pigment, nitrosohemochrome light pink in color.
The Sodium Nitrite (NaNO2) is added directly to meat by using Instacure 1 mix. Note : 50 ppm or more of nitrite is needed for the proper development of the curing color. Curing meats with nitrite amounts over the maximum established limits will usually give a yellowish-green color to hams, most noticeable in the fatty tissue. Cured meat will develop its true cured color only after submitted to cooking (boiling, steaming, baking) at 140° 160° F. This color is largely dependent on the amount of myoglobin that a particular meat contains. Darker meat contains more myoglobin than lighter meat and going from top to bottom :
The amount of myoglobin in different meats is as follows:
Meat Myoglobin (mg/g)
Beef 4 - 10 milligrams per gram of beef
Lamb 3 - 7
Veal 2 - 3
Pork 2 - 7
Poultry Dark Meat 2 - 3
Poultry White Meat 1
The meat that contains the most myoglobin will have a darker red color after curing.
Fish float in water and don't need constant muscle energy to support their skeletons. Most fish meat is white, with some red meat around the fins and tail, which are used for swimming. Most of the fish don't have myoglobin at all. There are some antarctic cold water fish that have myoglobin but it is confined to the hearts only (flesh of the fish remains white but the heart is of the rosy color. The red color of some fish, such as salmon and trout, is due to astaxanthin, a naturally occurring pigment in the crustaceans they eat. After all myglobin has gone into reaction with NO, the color of cured meat has been determined and adding an additional amount of nitrite (Instacure 1) will not change the result. The excess nitrite will have to be eaten by a consumer. By the same token, an insufficient amount of nitrite will not cure meat properly and the color will not be right even when given enough time. When to use nitrate and when nitrite?
Because nitrate first has to be converted into nitrite before the latter can start curing we can draw a logical conclusion that nitrate works slower than nitrite. That is why it is used in the production of dry sausages that need at least 4 weeks time to mature and thus will provide a continuous and slow supply of nitrite over this extended period of time. For the same reasons it is used for production of large hams. The old saying “time is money" applies to curing as well. Hams cured with a traditional nitrate pickle will develop proper color in about 60 days. The same hams cured with nitrite pickle need about 30 days for the right color to develop. To make dry sausage we use Instacure 2 which is a mixture of slow acting nitrate (main ingredient) and fast acting nitrite (small percentage). That way nitrite will start curing meat immediately after mixing and after a while nitrate (by releasing nitrite) will take over and continue the process. Curing times for meats used in production of sausages are very short and Sodium Nitrite (Instacure1) is used as it does not rely on help from bacteria and will react with meat immediately. Nitrate works best at 46º-50º F as at these temperatures bacteria that will release nitrite is very active. That was fine in post war Europe when people did not have refrigerators. On the other hand, those higher temperatures (46º
50º F) are an open invitation to different types of bacterias that can spoil the meat or develop toxins and that is not acceptable for commercial plants that need to produce a product with the maximum shelf life. Here we have a little dilema those nitrite producing bacterias are rather dormant at the recommended curing temperatures below 41º F ( 5º C) but the best conditions for the nitrate action are at 46º 50º F (8º
10º C). For those reasons to the mixture of salt and nitrate we add a little amount of sodium nitrite so we can jump start the curing process at recommended low temperatures. Once the sufficient amount of salt will penetrate the cured meat it will act as a barrier to the growth of bacterias and the curing temperatures could be higher hams could be safely left hanging and air dryed as it was done in Spain and Italy for centuries. Now at those higher, but favorable for nitrate temperatures, nitrate kicks well into the action by slowly but continuously releasing a fresh suply of nitrite. Trying to air dry ham by using nitrite alone will not do the trick as the nitrite will dissipate in a few weeks and nothing will be left to cure the meat that has to hang for 6 months more.