Brine Curing Ham and Food Safety

[elham]

Okay I have a series of questions related to Brine (salt) / Sweet (sugar added) Pickle Cure formulation and process specifically to whole fresh bone-in hams, so I wanted to start this with what seems a rather simple / straight forward question: “What is the cure meant to cure?”


The National Center for Home Food Preservation (NCHFP) has a web page entitled; “Curing and Smoking Meats for Home Food Preservation,”


https://nchfp.uga.edu/publications/nchfp/lit_rev/cure_smoke_pres.html


with reference to USDA Publications specifically USDA Ham and Food Safety for purposes of this discussion.


https://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/meat-preparation/ham-and-food-safety/CT_Index


In “Curing Solutions” this document states; Nitrite and salt inhibit the growth of Clostridium botulinum a deadly microorganism which can occur in foods under certain situations.


In “Smoking and Smoke Flavoring” this document states; “Smoking . . . slows the development of rancidity” (however “rancidity” alone typically is not likely to produce immediate illness or harm).


In “Foodborne Pathogens” this document states; “The food borne pathogens that can be found in pork are Escherichia coli, Salmonella, Staphylococcus aureus and Listeria monocytogenes” . . . “all destroyed by proper handling and cooking to an internal temperature of 160oF”. It goes on to state; the following pathogens are associated with ham: Trichinella spiralis (trichinae), Staphylococcus aureus (staph), and Mold, noting specifically that “dry curing may or may not destroy S. aureus” implying but not specifically stating that; “high exterior salt content” is the preventative element (inhibiting bacterial growth) but no mention is made or extended to brine cured meats. It also mentions molds producing mycotoxins, but without specifically stating so dry cure is implied wherein it states; “molds grow on hams during the long curing and drying process”


According to Wikipedia “C. botulinum is only able to produce the neurotoxin during sporulation, which can only happen in an anaerobic environment.” Anaerobic (appears to mean without oxygen) and one would assume therefore, that the whole point with regard to ham, is that the application of smoke could produce an anaerobic environment wherein the botulism toxin could grow.


All that for this one question - Is the sole food safety function of cure (salt with added nitrate or nitrite compounds) to prevent Clostridium botulinum?

 

[dr k]

I can't remember where I read this but NO3 nitrate breaks down to NO2 nitrite then to NO nitric oxide and is an oxidizer. It works on an atomic level stealing electrons, changing atomic structure and in this case with molecules being bacteria when that structure changes then it dies or self destructs as well with all kinds of microbes. It binds with the iron ion in myoglobin, keeping it from oxidizing (rusting turning brown), locking in the natural pink color longer before spoilage. Hearty spore producing bacteria that produce toxins like Clostridium Botulinum are talked about a lot with heating, pasteurization and sterilization of food, being anaerobic bacteria. Spore producing bacteria since they seem to more quickly reproduce in temps that are unfavorable to other non spore producing bacteria are mentioned more so within articles instead of all foodbourne pathogens but I don't know if it's sole food safety function is/was for C. Botulinum.

 

[dr k]

Inhibition of microbial growth[edit]
Sodium nitrite is well known for its role in inhibiting the growth of Clostridium botulinum spores in refrigerated meats.[14] The mechanism for this activity results from the inhibition of iron-sulfur clusters essential to energy metabolism of Clostridium botulinum.[14] However, sodium nitrite has had varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms.[9]Even though the inhibitory mechanisms for sodium nitrite are not well known, its effectiveness depends on several factors including residual nitrite level, pH, salt concentration, reductants present and iron content.[15] Furthermore, the type of bacteria also affects sodium nitrites effectiveness.[15] It is generally agreed upon that sodium nitrite is not considered effective for controlling gram-negativeenteric pathogens such as Salmonella and Escherichia coli.[15]

 

[elham]

DrK,


That is very interesting, thank you. I’m not sure where the second post is taken from, but I was interested to read that; “sodium nitrite has had varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms”, but they do not mention what if any those might be, except to exclude its effectiveness with regard to Salmonella and Escherichia coli.



I kind of heard that the NO3 (Nitrates) breakdown into NO2 (Nitrites) over time and that they were responsible for the pink set of the myoglobin in things like hams and corned beef, but not at that level of detail. (I believe that same NO component, produced in wood combustion occurring at elevated temperatures, combines with the myoglobin and is what produces the smoke ring in wood smoked products). I also suspect that is why cures which combine nitrates and nitrites (cure #2) are typically used for long term preservation (like shelf stable cured ham or fermented dried sausages) whereas cures (cure #1) with only nitrites are typically used for items to be cooked and eaten quickly (like smoked kilbasa or other sausages). It seems logical that the slow breakdown of nitrates into nitrites over long periods of time, along with the high salt content are what allows the meat to remain spoilage resistant for months in moderate temperature without refrigeration.


So what differentiates smoking cured meats from non-cured meats?


If one can smoke a large non-cured bone-in pork butt at a reasonable temperature (above 225oF) without issue, why is a cured ham so significantly different? It appears to me that (barring actual preservation to a shelf stable state) that most hams today are cured to achieve, not shelf stable preservation, but rather the texture and taste of cured meat. So here I am going to somewhat try to answer my own question. The time at refrigeration temperature required for curing is what forces the need for curing. (That and the injection of cure, if used, requiring multiple injections near the bone and/or throughout the meat would possibly introduce pathogens from the surface into the core of the meat).


Following on from that assumption; once cure is introduced, it needs to meet the all the cure concentration requirements for maximum and minimum quantities determined either by weight or by solution for an equilibrium brine or sweet pickle cure.


Here is where I really get confused. There appear to be differing formulas and concentrations for pumping solution by weight, brine or pickle cure, dry rub, etc. All of these appear aimed at producing a product with a final ppm concentration of nitrite. The formulas for cure composition seem very exact, and then this super precise formulation appears to be contradicted by a wild swing in the “time in cure / absorption” part of the formulation (largely based on either weight or thickness of the meat) to get to the final ppm concentration in the finished product.


So the questions is really this;

1) In talking specifically about brine or sweet pickle cure, is there a set range for all components in the cure formulation?

2) Once that formulation is determined, is there an accurate means of determining the minimum and maximum time in solution for both a safe and edible product?

3) Is that/are those formulations explicitly dependent on other ingredients such as proportion of salt and sugar or merely nitrites? (I read somewhere that salt was critical for absorption, but that the sugar basically had no safety impact other than possibly slightly extending curing times).

4) Are formulations for cure #1 (nitrites only) different from those for cure #2 (with both nitrate and nitrite)?

5) Many ham brine cures (“Pops Cure” for example) are cure #1 based (nitrite only). If not trying to produce a shelf stable product, is there any use or advantage to using cure #2 (with both nitrate and nitrite present)?

6) Can brine / sweet pickle curing even produce a shelf stable product, or are they only for hams intended to be immediately cooked after curing and equalization (either boiled, roasted, or smoked) to internal safe temperature?

 

[dr k]

What

 

[dr k]

Smoking cured meat allows more time in the danger zone when cold smoking.

 

[dr k]

Pop's wet brine cure is a equilibrium cure so the solution is 2x the strength before meat goes in then 1 to 1 equal parts outside the meat and inside so you can't over cure and it can be in the cure past the recommended duration for that cut till you get around to deal with it. Most people use nitrite since it breaks down when cooking compared to more stable nitrate. Then there's Tender Quick blend of nitrate/nitrite I haven't tried dry curing. Nitrate can't be used in commercial bacon curing. The Clostridium Botulinum needs the Iron-sulfur in meat or myoglobin for metabolizing purposes to live. NO binds to iron to keep it from oxidizing, keeping it from turning brown. Thie common factors appear to be iron related and a lot of dialogue on ions, electrons and oxidizing. The more I read it seems NO is for inhibiting C. Botulinum but inhibits other microbe growth except salmonella and E. Coli. I do have other bookmarked sources on my laptop I can put up links. This is the extent of my interest of this science. Digging dog farms has a 156ppm nitrite calculator. I believe cure 1 should penetrate without added salt and sugar since it's 6.25% nitrite and 93.75% salt and some dye. The digging dog farms calc is for dry curing and you need to add in the weight of water to the meat for wet curing. So a gal of water and 10lbs of meat comes to 21gms (1 round Tbsp of cure 1) which is basically Pop's wet cure.

 

[daveomak]

elhan, morning.... It's inspiring you have questions about the different curing methods and ingredients associated with those processes...
Folks take information from the FSIS and try to use those "rules" for home curing... WRONG.... In commercial processing, injections of the "cure" are used... The meat is weighed before and after injecting for a baseline "take up" in the meat to measure the ingredients in the meat.. and extrapolated for further batches of meat..
Meat thickness, pump pressure and needle travel speed are all factors that affect "take up"... I've worked, as a contractor, in a meat processing facility... I've seen those "take up" values go haywire.... One supplier of pork bellies change the parameters without notifying the meat processor... It resulted in a change in "bellies per ton" that were delivered... The exact number I do not know... The results were reduced "take up" of the curing solution in the bellies... which in turn affected the final weight and significant loss of profit for the processor BECAUSE they had determined the final weight of the bellies based on the original baseline testing of "take up"... It is a really scientific process that takes diligence to maintain...
All that being said, DO NOT USE PROCESS CONTROL CURING in the home...
Weigh each individual hunk of meat... weigh out the ingredients based on USDA recommendations....
As Dr K has noted.... and I have determined for my own personal use....
Salt additions of 1.75-2%, sugar at 1%, and cure#1 at 0.25% ... based of the weight of the meat will return a safe product from the smokehouse....
For injecting, the above numbers work perfect... Add those weights to 5-10% the weight of the meat in liquid as an injection solution... Then inject ALL of the solution into the meat.. insuring coverage of the bones and joints... and you are golden... The minimal amount of solution does not affect the quality of the meat... As the solution evaporates, the ingredients are left behind in the meat...
For equilibrium brine curing...
weigh out 25% the weight of the meat in the brine liquid...
weigh out ingredients for the curing step and include the weight of the brine liquid and meat... dissolve the ingredients and inject up to 80% of the brine/cure into the meat and bag it and remaining cure .. refer the meat and remaining cure in the refer for 2-4 weeks to equilibrate.... turn the bag every few days....
Using the above methods insures all the necessary ingredients are or will be in the meat...

 

[elham]

Hey all, thanks for the replies. Apologies that it has taken me so long to get back to this, but work keeps interfering with my hobbies.


So Dr K – can I deduce that the cure formulation at 6.25% nitrite and 93.75% salt has sufficient salt to carry the nitrite and that for absorption considerations only (excluding all other preservative properties of salt); one could cure with no additional salt other than that inherent in the cure mix?


Everything I have read would appear to indicate that salt is critical to the curing process (beyond mere absorption) and that something like 1.5-2% is good for wet cure and 3+% appears to be common (if not necessary in dry cure), but let’s concentrate on wet cure for now. This sort of leads me into my next series of questions.


Daveomak - thank you for your responses. That is very much what I am looking for; however, you talk about “take up” and mine is slow, so please forgive in advance the coming onslaught of questions.


You indicate “Salt additions of 1.75-2%, sugar at 1%, and cure #1 at 0.25% based on the weight of the meat will return a safe product from the smoke house”


1) In that formulation:

a) Are those percentages to be based on weight of meat of alone, or weight of meat plus water?


b) As Dr K notes, ppm calculations for wet curing appear to require inclusions for the weight of water. I would assume that since the weight of the cure mix is so small that it itself does not impact the outcome by any significant value; however, does the formulation also need to (should it) include the weight of dry ingredients such as added salt and sugar?


c) In the formulation, is the 1.75% salt by weight a USDA minimum value for wet cures?


d) If not, is there one established by USDA or others for wet cure?



e) Is there a different / higher published minimum salt value by weight for dry cure?


f) It appears the ppm calculation for brine cure must take into account the weight of the liquid or water, but speaking specifically to salt content; are those percent values of salt (one wet curing / one for dry curing) interchangeable except for the inclusion of water weight or does dry curing require a higher percentage of salt by weight of meat to produce a safe product?



g) The addition of sugar does not appear to be necessary other than to subdue the salt flavor. I assume one can produce a safe cure with no sugar in the formulation. (Sugar, like added spices, appears to have no other function than for adjustment of the finished flavor profile). However, is there a published or reasonable upper safe limit for the addition of sugar or spices?


Again, apologies - those questions first; but many more to follow.

 

[daveomak]

https://nchfp.uga.edu/publications/nchfp/lit_rev/cure_smoke_toc.html

 

[dr k]

I read from others that the cure has the ability to penetrate on its own. It would be bland. Adding dissolvable salts and sugars increases the flavor, density/specific gravity of the solution so it will push/osmosis into a less dense solution (myglobin and less dense liquid proteins) until the inside and out are of equal concentrations over time. I do pops wet cure with 21 grams (1 heaping Tbsp cure 1) and just 1/3c sugar, 1/3c brn sugar, 1/3c kosher salt and 1 gal water. If it covers, it cures. I put everything in my curing vessel in it's original packaging and fill in 1/2 gal incements till the water line is over the meat for water needed, then make gal or 1/2 gal cure.

 

[elham]

Daveomak – Like I said, I am slow, so stick with me here.


I have poured through the document you linked for days and hours on end. I find it to be ill contrived, at the very least confusing, and in many ways conflicting. I have not found answers to my various questions therein.


I guess I really need to extend my reading to the cited references to see if in those documents I might find some sort of enlightenment or only further confusion.


Table 5.3 indicates minimum salt by percent concentration for the listed pathogens ranging from 2-20% with all but Campylobacter significantly at 8% or above (read that as “inedible”). Now it does indicate that the factors (pH, salt, temp, and oxygen) can “act in concert to prohibit the growth of pathogens” but gives no clear correlation or calculation for conglomeration of factors to get there. Again, to me, it seems to be a collection of very exact scientific based facts, values, and theories that are then executed almost literally with a smoke and mirrors, bit of this bit of that, approach to actual application.


2.3.1. Prague Powder #1, Insta Cure, or Modern Cure.

This cure contains sodium nitrite (6.25%) mixed with salt (93.75%). Consumers are recommended to use 1 oz. for every 25 lb. of meat or one level teaspoon of cure for 5 lb. of meat.

6.2.3. Curing Compounds

Purchase commercially prepared cure mixes and follow instructions carefully (PHS/FDA 2001) or blend cure mixes carefully at home using an accurate scale.

Nitrite. Use cure mixtures that contain nitrite (e.g., Prague Powder 1, Insta-Cure 1) for all meats that require cooking, smoking, or canning (PHS/FDA 2001). Dry cure using 1 oz. nitrite per 100 lbs. meat maximum. For sausages use ¼ oz. per 100 lbs. (Reynolds and Schuler 1982). A 120 ppm concentration is usually sufficient and is the maximum allowed in bacon (PHS/FDA 2001).

Let’s forgo the fact that there are mixed measures (both weight and volume/pound).


At 2.3.1; nitrite (6.25%) mixed with salt (93.75%) applied at a rate of 1 oz. for every 25lbs. of meat.

At 6.2.3; Dry cure using 1 oz. nitrite per 100 lbs. meat maximum. No minimum value or absorption rate (time in cure) is stated.

(Also a vague statement about 120 ppm being “usually sufficient” and the maximum allowed in bacon . . . is not “usually sufficient” and “maximum allowed” somewhat of an ox-like-moron)?


I have to assume that the “1 oz. nitrite per 100 lbs. meat maximum” measure given at 6.2.3 is for straight nitrite, not cure mix, even though the the paragraph begins “use cure mixtures that contain nitrite . . . “. If you interrupt that to read “apply not more than 1 oz. of nitrite to not less than 100 lbs. of meat” (rather than the ill-conceived way in which it is written “apply 1 oz. of nitrite for anywhere from zero to 100 lbs. of meat”); then that assumption being true, keeping the measures consistent throughout the document for better understanding would mean “do not apply more than 1/4 oz. of straight nitrite per 25 lbs. of meat” (correlating 2.3.1 and 6.2.3).


Unless my math is off:

1 oz. of cure mix at 6.25% nitrite = 0.0625 oz. straight nitrite per 1 oz. of cure.

1 oz. of cure per 25 lbs. meat (2.3.1) = 4 oz. cure per 100 lbs. of meat

0.0625 oz. straight nitrite/1 oz. of cure x 4 oz. cure = 0.25 oz. pure nitrite per 100 lbs. of meat

(Well below the maximum application rate of 6.2.3, if that is what that really is).


However; nothing therein tells you that 1 oz. of cure is the minimum allowable amount to produce a safe product, and nowhere in that document does it even broach the subject of time in cure or rates of absorption.


So where am I missing it?

Time in cure appears to have a very significant impact on base nitrite levels in the product as it comes out of the wet cure (which I would also assume also translates to a value of residual nitrite in the final cooked product). Should one assume that a 15 lb. ham soaked in wet cure for 1 hour will produce the same product saturation as that same 15 lb. ham left in the same wet cure for one month?


How does that work?

 

[daveomak]

Good questions... The variety of curing options, depending on the use of products and methods, is varied as you have noted... When reading the FSIS/USDA technical bulletins or technical manuals, one has to have an understanding of the subject at hand...
Not all meats are cured alike... Not all processes are treated the same... Not all bacteria have the same threshold for destruction using salt... Not all pathogens have the same threshold for destruction using heat...
1 oz. per 100#'s equals 625 Ppm... Not safe to use in sausage, but safe as a maximum allowable, for some processes...
When reading commercial processors handbooks and understanding them, one needs a bit more than a backyard degree in sausage making...
Let me go a bit further... when making some meat products, you are limited to the amounts of cheeks, liver, tongue etc. just to give your product a name... some chicken or turkey "may" be allowed but only up to a certain %age..

I believe I noted somewhere above, don't try to understand the commercial processors rules etc. and convert them to home use.... It usually don't work..
There is no way I can satisfactorily explain all this stuff to you.... I ain't even gonna try....
Enjoy your new found "Self educational tour..."

 

[elham]

Thank you all for your responses. It's the OCD and the engineer in me that not only wants to know exactly why and how it works, but also thinks that everything in the world should have a very specific formula operable within a defined set of parameters. Looks like the complexities of curing are such that there are no simple or set fast answers.

Looks like I'll be chasing my tail around for a while until I wear myself out.