deuce, morning..... this explains the difference between nitrite and nitrate curing temps..... Nitrate need bacteria to convert to nitrite... bacteria needs a higher temp to grow... therefore when using nitrate to cure meat, temps in the range of 46-50 degrees F are preferred... and the length of time needs to be extended for bacteria to grow and the nitrite conversion to take place... Dave
Curing Temperatures
The curing temperature should be between 36-40° F (2-5° C) which falls within the range of a common refrigerator. Lower than 36° F (2° C) temperature may slow down the curing process or even halt it. Commercial producers can cure at lower temperatures because they add chemicals for that purpose. There is a temperature that can not be crossed when curing and this is when meat freezes at about 28° F (-2° C). Higher than normal temperatures speed up the curing process but increase the possibility of spoilage. This is a balancing act where we walk a line between the cure and the bacteria that want to spoil meat. The temperature of 50° F (10° C) is the point that separates two forces: below that temperature we keep bacteria in check, above 50° F (10° C) bacteria forces win and start spoiling the meat.
Meats were traditionally cured with Nitrate. Before Nitrate can release nitrite (the real curing agent) it has to react with bacteria that have to be present in the meat. Putting Nitrate into a refrigerator kept solution (below 40° F) will inhibit the development of bacteria and they may not be able to react with Nitrate. On the other hand sodium nitrite works well at refrigerator temperatures. When used with Nitrates/nitrites, salt is an incredibly effective preserving combination. There has not been even one documented incident of food poisoning of a meat cured with salt and Nitrates.
People in the Far East, Africa, South America and even Europe are still curing meats at higher than normal temperatures without getting sick. That does not mean that we recommend it, but if someone in Canada shoots a 1600 lbs (726 kg) Moose or a 1700 lbs (780 kg) Kodiak Bear he has to do something with all this meat. He is not going to spend 5,000 dollars on a walk-in cooler, is he? These are exceptional cases when curing can be performed at higher temperatures. After the Second World War, ended most people in Europe neither had refrigerators nor meat thermometers, but were curing meats with Nitrate and making hams and sausages all the same.
Because of primitive conditions the curing temperatures were often higher than those recommended today but any growth of C. botulinum bacteria was prevented by the use of salt and Nitrates.
They also predominantly used potassium Nitrate which works best at temperatures of 46-50° F (8-10° C) and those were the temperatures of basement cellars. There was not much concern about longer shelf life as the product was consumed as fast as it was made. Salt and nitrite will stop Cl. botulinum spores from developing into toxins, even at those higher curing temperatures. Due to increased bacteria growth at those higher curing temperatures the shelf life of a product would be decreased. Remember when handling meats, the lower the temperatures the slower the growth of bacteria and the longer life of the product. Extending the shelf life of the product is crucial for commercial meat plants as the product can stay on the shelf longer and has better chances of being sold. Curing is a more complicated process than salting. In addition to physical reactions like diffusion and water binding, we have additional complex chemical and biochemical reactions that influence the flavor and color of the meat.