by vagreys » Tue Sep 25, 2012 5:35 pm
Short answer: yes, you can safely use saltpetre. Your caution is commendable. Yes, there are maximums. No, there is no simple answer.
Expansion: There are maximum amounts of sodium and potassium nitrates allowed in cured meats, and the maximums vary from country to country, with respect to commercial products. Even in our home sausage making and curing, most of us try to adhere to some standard to ensure that our products are safe for those who will consume them (safe from excess nitrites/nitrates, and safe from botulism).
How much saltpetre you put in your brines depends on how you are using the brines (immersion to equilibrium, immersion to percentage gain, percentage pump, etc.). There is some guesswork involved. Government guidelines discuss the difficulties of predicting and measuring final nitrite/nitrate levels vs in-going nitrite/nitrate. Also, it depends on the amount of brine/cure you are using - the amount of pure saltpetre you add is very small, comparatively speaking, and in small batches, using pure saltpetre can be difficult. For small batches, the uniform distribution of Cure #2 can be a better option.
First, you have to decide whose maximum levels you want to use - US, UK, EU, AUS, some other country? Then, you have to consider what cure method you want to use with that in mind. Then you have to consider the amount and shape of meat you are curing and how that affects curing time and pick up of the nitrate. There are formulas for determining how much nitrate to add, based on this information.
Commercially, in the US and EU, nitrates are no longer permitted in bacon, due to the risk of nitrosamine formation during cooking, so you would use no saltpetre at all, if following modern guidelines. I think some dry-cured, long-maturing bacon is allowed to contain nitrate, with the idea being that the nitrate will have broken down into nitrite and dissipated before the consumer uses the product.
Hope this gives you a little more to consider, to refine your questions.
ETA: If the ONLY reason you want to add saltpetre is for color, and none of its preservative qualities, then you might want to consider using Cure #1 with sodium nitrite, instead of pure potassium nitrate. If you are confident of your cure, otherwise, then you may want to consider other alternatives for fixing color, like ascorbic acid.
- tom
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