Also FYI most "nitrate free" cured meats just substitute celery powder for sodium nitrate as celery has naturally occurring nitrates.
Don't believe me check this out....
http://ruhlman.com/2011/05/the-no-nitrites-added-hoax/
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Unfortunately, nitrate needs bacteria to convert to nitrite.... bacteria will not flourish below 40 degrees F and therefor will not convert the nitrate to nitrite, which is necessary to prevent botulism.... nitrate should be used when meat products are "aged" at temps around 50 degrees F.... The conversion to nitrite takes time... lots of time... months... that's why is it used in slow curing/drying of meats...
http://www.susanminor.org/forums/showthread.php?736-Curing-Salts
Sodium Nitrate and its chemical equivalent potassium nitrate are interchangeable. For the most part potassium nitrate has been replaced with sodium nitrate – which is considered more stable and reliable; both are extremely poisonous. These ingredients are still widely used for home curing outside the United States, but it is recommended that these cures should only be used in it pure form by meat processing plants. In such plants this is done by trained personnel under strict supervision. Therefore it is highly recommended when using nitrates to obtain it in premixed cures that can be safely and accurately measured; such as in cure #2, and the Morton cures which are discussed in more detail latter on.
Nitrates are considered a slow cure, and are referred to as a “time release capsule.” It does not cure meat directly and initially not much happens when it is added to meat. With nitrates the curing is dependent on the amount of bacteria present, and the environment (temperature) the bacteria need to grow. For nitrates to work as a cure it requires the presents of certain microorganisms. These microorganisms are present in all meats, and start to react with the nitrates to reduce them to nitrites. It is the nitrites that will start the curing process.
This is a slow process that steadily releases nitrites over a long period of time. This makes it well suited for curing products that require long curing times. Dry cure products can take as long as several weeks to several months to fully cure. Nitrates are used for making dry cure sausages; such as pepperoni, hard salami, geonoa salami, dried farmers sausage, capicola, etc, and dry cure meats that are not cooked or need to be cooked.