Is this too much cure # 2

Tips and tecniques on dryng drying, curing etc.

Postby wheels » Mon Feb 02, 2009 10:21 pm

I've just noticed that the document I mentioned above has already bee pointed out by Parson Snows in this thread:

http://forum.sausagemaking.org/viewtopic.php?t=327

...and was already sat on my computer, I must have downloaded it to read, and never got around to it. :oops:
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Postby Batman » Mon Feb 02, 2009 11:48 pm

TLP, the other variable that hasn't been mentioned is the homogeneity of the curing mix. You cannot assume that through simple mixing the small amount of nitrite is evenly distributed in the salt/sugar, and therefore the actual amount of nitrite in contact with the meat could be anything from 0-100%, and whilst it might be reasonable to assume an even distribution, the difference in particle size and density might make that assumption false.
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Postby This Little Piggy » Tue Feb 03, 2009 4:45 pm

Good point, Tony.

Reading through the EU document Phil has pointed us to, as well as other sources, I've also been intrigued by the role of ascorbic acid and its relative erythorbate in curing. It seems three-fold.

One, it accelerates curing, in the sense that it speeds up the reduction of nitrite to nitric oxide, and thereby reduces the residual levels of nitrite more quickly. In general, this seems like a good thing, but I wonder if it would be detrimental for something that requires a longer curing time like a whole ham. In other words, is there a concern about nitrite being reduced before it has penetrated all the way to the center of a ham? In table 10, on page 21, they show the effect of adding 1000 mg of ascorbate per kg of meat is to reduce all the nitrite in 5 days. Since it takes weeks for the cure to penetrate to the center of a ham, it seems like this would lead to uneven curing in this case.

The second benefit of ascorbic acid is that is also seems to inhibit the formation of nitrosamines when cured meats are cooked and digested. Since nitrosamines are the by-product of nitrites that cause the greatest health concern, this is also for the good.

Finally ascorbic acid is an antioxidant, so it helps to prevent oxidation of the fats in cured meats which can lead to off flavors. I've poked around a little bit to see if anyone thinks the addition of ascorbate is detrimental to the flavor of cured meats, but haven't found anything so far.

None of the sausage-making books aimed at an amateur audience that I'm familiar with makes any use of ascorbic acid, although it sounds like it's been in industrial use for decades. Is this a case of industry actually being ahead of the game?
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Postby wheels » Tue Feb 03, 2009 6:00 pm

TLP

You've summed its uses up nicely.

I too share some of your concerns about the speed of reduction of the nitrite. Particularly in view of the low recommended ingoing amounts of nitrite. Perhaps we're wrong about the amount of time the cure takes to get to the middle of the meat? I think it's this concern that leads many of us to use a pump method or Oddley's pump then dry cure. Certainly I know that only very low levels of nitrite are needed for colour once in the meat - I've used very low amounts to give pâté a good colour. Mind you that's a ground product. The table you refer to about reduction of nitrite was for a 'pork slurry', so perhaps we are reading too much into it. Whole muscle would produce different results?

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.


It goes against what I, and I'm sure many others, thought.

I am surprised by how confident they seem that comprehensive protection will be offered by, what is in terms of the US law, a low level of Nitrite.

Another thing that strikes me, worryingly so in this case, is the fact that the EU law-makers reduced the previous standard level of nitrate to 150PPM to 150PPM - something that doesn't seem to be advised by EFSA.

Most of my cures are fairly low level nitrite/nitrate and so aren't above the nitrite level recommended. As regards nitrate, I feel that I shall probably continue to use the old 300PPM EU standard. I trust the scientists more than the politicians!

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Postby Batman » Tue Feb 03, 2009 6:02 pm

TLP,

1 Difficult to say without more information on how it works. A number of people in this forum have been using ascorbate in bacon dry cures for a while now and haven't reported any problems with curing as far as I know. Maybe we can leave the issue of adding to air dried hams for another thread :)

2 The issue of nitrosamine formation only seems to have been raised in relation to high temperature cooking of bacon. However, I'n pretty sure that there is no confirmed link between nitrosamines and cancer in humans. So you can take this as a preventative measure or unnecessary depending on your point of view.

3 Whilst ascorbate is an anti-oxidant, because it is water soluble, it has no effect on fat (Wikipedia). I'm not so sure that it is widely used in meat processing but certainly other industrial food processing.
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Postby Batman » Tue Feb 03, 2009 6:23 pm

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 :D
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Postby saucisson » Tue Feb 03, 2009 6:41 pm

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.



I think this is part of the hurdle effect, once the meat is fully cured it has lost enough moisture so that the bacteria cannot grow, so the nitrite has done it's job protecting the meat until it reaches this safe point.

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Postby wheels » Tue Feb 03, 2009 8:38 pm

Dave

That's logical, but...

...will the AW be below 0.96 or PH below 5 at the end of curing with nitrite?

I know they're the figures quoted for safety against Clostridium botulinum in fermented sausage. Help, I'm getting out of my depth!

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Postby This Little Piggy » Tue Feb 03, 2009 11:48 pm

Tony,

1) 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. Using more nitrate and less nitrite could be a hedge here, since the nitrate would first need to be reduced to nitrite. But it just seems safer to avoid ascorbate and related forms in any slow-cured item. If it's going to be months (or years) before a meat product is consumed, then there seems to be little need to accelerate the reduction of nitrite, as this will occur naturally. On the other hand, if nitrite is added (perhaps more for color or flavor) to something that will be consumed within a week or two, then ascorbate seems to be a useful additive to ensure a rapid reduction and low residual levels.

2) Nitrosamines are also be formed in our digestive system from any residual nitrites in the food we consume. While we get far more nitrates (and thereby nitrites) from vegetables than we do from cured meats, the links between nitrosamines and cancer are pretty clear. Writing on the carcinogenic properties of nitrosamines and N-nitroso compounds, Richard Scanlan writes, "Approximately 300 of these compounds have been tested, and 90% of them have been found to be carcinogenic in a wide variety of experimental animals. Most nitrosamines are mutagens and a number are transplacental carcinogens. Most are organ specific. For instance, dimethylnitrosamine causes liver cancer in experimental animals, whereas some of the tobacco specific nitrosamines cause lung cancer. Since nitrosamines are metabolized the same in human and animal tissues, it seems highly likely that humans are susceptible to the carcinogenic properties of nitrosamines."

3) As I understand it, that would be right: ascorbate "has no effect on fat." But, by tying up oxygen, it prevents the oxygen from reacting with fat and thus prevents the off-flavors that you get with oxidation. This makes ascorbate particularly useful with anything that will be cut into over a period of time, leaving a surface that is exposed to the air.

Phil,

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. One, the nitrites inhibit the growth of a wide range of bacteria responsible for spoilage and/or illness. Second, the salt lowers the water activity (Aw) that microorganisms need to thrive. Fresh meat has a water activity level just below pure water at .99. When salt (usually about 3%) is added to ground meat, it immediately drops this to about .96, offering another hedge against bacterial growth. With a dry-cured product, like a ham or a salami, the water activity level will drop to .87 or lower, offering further protection, but it could take months or years to get there. There's the rub! The concern with dry-curing a big hunk of meat like a ham is that, no matter how much salt you cover the surface with, the inside of the ham will still have a high water activity level for weeks, and thus be at risk for spoiling. Since most bacterial contamination is on the surface, the surface coating of cure is fairly effective, but I have seen spoilage figures for dry-cured hams, particularly ones cured without nitrate/nitrite, of around 20%.

Nitrites also do not contribute to lowering the pH, which is another hedge against undesired bacteria. That's the work of other bacteria, mainly lactic acid ones, specific strains of which are supplied in commercial sausage cures. There are probably some naturally-occuring bacteria that will lower the pH in a ham, but not significantly in my experience.

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.
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Postby Batman » Tue Feb 03, 2009 11:55 pm

Phil, probably not, but the nitrite should have killed any Clostridium spores present in the meat and the AW and pH (at least for salami type products using an acidifying agent) will be well on their way.

We rightly take precautions to prevent Clostridium because of its potential deadly effect but being anaerobic I suspect it is not easily cultured in home products.

I think I've posted before that the HPA identify only 33 cases in the UK between 1980-2006, 26 of which relate to hazelnut yoghurt in 1989 (I remember that) and all but 1 of the remainder were home produced produce from Europe, none were home produced in the UK.

It seems to me that following simple basic hygiene procedures is the main defence against bacterial and other problems.
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Postby wheels » Wed Feb 04, 2009 3:13 pm

TLP

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.


Yes, these are around the levels I generally advise when answering queries on the forum.

In a cure mix containing nitrate/nitrite, there are 2 things going on...

Nitrites also do not contribute to lowering the pH...


Sorry, perhaps I misled you. I am aware of what you explain - I was just expressing my incredulity that we could be certain a low enough AW could have been reached to protect the meat without ongoing chemical based support.

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.


But are we just talking about dry cured ham? EFSA are talking about all meat products.

In your reply to Tony you say:

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.


It's a good point. However, the research EFSA quote was based on the effect of nitrite in a pork slurry. Perhaps it takes longer in solid muscle?

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 :D


...and complicated by EFSA saying "There is no direct relationship between the input nitrite and the residual nitrite..."

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Postby saucisson » Wed Feb 04, 2009 4:35 pm

Raw meat has a water activity of 0.98, you only have to drop to 0.91 wa to inhibit most bacterial growth. At these lower water activities the effect of pH becomes more pronounced, for example at 0.92 wa bacteria cannot grow below pH 4.2.
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Postby wheels » Wed Feb 04, 2009 4:58 pm

Yes that's true, but I think there's a lot more to it than that, otherwise why wouldn't the EFSA scientists just have given an Aw or Aw/pH criteria to be met?

Please note, I am not questioning or disputing any of the figures you or TLP gave. Just saying that I don't think they are the (complete) answer in this case.

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Postby This Little Piggy » Wed Feb 04, 2009 6:11 pm

Traditionally, meat was preserved by drying it out and acidifying it, but these processes take time�unless you're making jerky!

Because time is money, I imagine part of the prevalence of nitrites in cured meat today is just that they're quick and easy. Add a nitrite and salt cure to a sausage mix and you're done. Inject a cure into a ham and you're done and ready to sell it�with the addition of water to bump up the weight!

With good hygienic practices, it is entirely possible to cure a ham the traditional way, without nitrites. The reason for using them (separate from the question of the cured flavor they contribute) on this type of product is just to give you a hedge against bacteria while the salt does its work.

In his book, Dry-Cured Meat Products, Fidel Toldr� has a whole chapter on "The Manufacturing of Dry-Cured Ham." He has some interesting data on salt diffusion and changes in the water activity level in this product. According to him, it takes about 4-5 months before salt levels in the interior of the ham reach equilibrium with the exterior. As to water activity level, a chart on page 46 shows that it takes more than a month for the water activity level in the biceps femoris to reach .96 �the level that you reach immediately when you add salt to a sausage mix. A level of .91 might not be reached for close to a year. That's a lot of time for things to go wrong unless you hedge your bets with some curing salts.

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.

As for the EFSA conclusion that "there is no direct relationship between the input nitrite and the residual nitrite," I wonder if they meant to say that there is not "simple" or "universal" relationship since it depends on factors such as temperature, pH, length of cure, aging, etc. 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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Postby wheels » Wed Feb 04, 2009 8:29 pm

TLP

Interestingly, it would appear that Fidel Toldr�'s work was taken into account in the EFSA advice (see last para, page 11).

You said:
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.


EFSA said:
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.


I accept this but can't help but be a little bit amazed by it

You said:
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.


You know, having re-read, it I believe they are saying "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", and yes, it is very puzzling.

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