There is no convincing evidence that the residual amount of nitrite contributes to the microbiological safety of meat products. For example, in meat products containing ascorbate (or isoascorbate / erythorbate) the residual nitrite content is very low and sometimes below the level of detection, yet growth of C. botulinum is prevented.
wheels wrote:One bit that really interests me is:There is no convincing evidence that the residual amount of nitrite contributes to the microbiological safety of meat products. For example, in meat products containing ascorbate (or isoascorbate / erythorbate) the residual nitrite content is very low and sometimes below the level of detection, yet growth of C. botulinum is prevented.
As you point out, the finding that residual levels of nitrite do not contribute to microbiological safety is pretty liberating. If, once it has done its job of disabling bacteria, it is no longer needed, then we really can calculate ingoing nitrate/nitrite levels at a minimal amount to get the job done once and for all.
In a cure mix containing nitrate/nitrite, there are 2 things going on...
Nitrites also do not contribute to lowering the pH...
In a product like the dry-cured ham we've been talking about, after the initial inhibition of unwanted bacteria by the nitrites, you're just relying on the effect of the salt and an extended aging period to dry the ham out, lower the water activity level, and preserve the meat.
Adding ascorbate to a bacon cure doesn't seem problematic to me, since this usually only lasts a week. But if it takes 2 or 3 weeks for curing salts to reach the center of a ham, then the seeming effect of ascorbate to reduce all the nitrite within 5 days could well be problematic.
Batman wrote:Phil, I'm not sure that the issue of residual nitrite level is as strange as it first seems. What science there is indicates that it is NO2 that is the active agent for which nitrite provides a source. Assuming complete curing, if there is residual nitrite, this would suggest there has been an excess of ingoing nitrite. If curing is incomplete, then either there is insufficient natural reducing agent or conditions prevent the oxidation or the nitrites have not been equally distributed over the meat or....
So many questions , so few answers
And he does mention ascorbic and erythorbic acids (as well as their salts) being used as additives in a dry-cured ham, so apparently their acceleration of the nitrite reduction is not a problem for such a long cure.
Taken in conjunction with the tests for botulinum toxin that were made on every combination of factors tested, the presence of residual nitrite did not guarantee that the product would prevent growth of C. botulinum. Conversely, the absence of nitrite did not indicate that the product would support the growth of C. botulinum. The products that prevented growth of C. botulinum for the longest time at any storage temperature tested were those containing added ascorbate (or iso-ascorbate), which caused nitrite levels to decline rapidly and often contained no residual nitrite.
If they really mean that you can make a ham one day and get one level of residual nitrite and make another ham exactly the same way the next day and end up with a totally different residual level, that's very puzzling.
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