# Thermal Stability of Cure#1 – Kitchen Science Lab



## PolishDeli (Oct 14, 2019)

When mixing up a wet cure, some recipes say to use hot water to help the ingredients fully dissolve.  Other say not to use hot water because the sodium nitrite (NaNO2) in cure#1 breaks down when heated. 

Over the weekend, I did some kitchen science experiments and concluded that it is safe to boil your brine.  The NaNO2 does not disappear, even if you boil the brine for over an hour. [NOTE: Whether you boil your brine or not, make sure to cool it down before immersing/injecting your meat!]

Summary of experiment:
Mixed up some water+Cure#1.
Boiled it.
Tested the concentration at 1, 2, 5, 15, 30, and 60 min.

Conclusion:   The concentration of NaNO2 increased with boiling time.
It increased because the NaNO2 was staying put while the water was evaporating.

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More details:

Step (1) Get a Nitrite test kit. $7 on amazon.

Step (2) Mix up a 0.5ppm solution. 
This is a very small amount of Cure#1 – less than what my scale can accurately measure.  So I did this in two steps.  
(a) Mixed up a 100ppm solution (1.6g Cure#1 + 1000mL water) 
(b) Diluted it (5mL of the 100ppm solution + 995mL water). 

Step (3) Measure the NaNO2 concentration.

Step (4) let it boil.  Start the stop watch when the thermometer reads 100°C. Boil with lid on to minimize evaporation. 

Step (5) Pull out a few mL at 1, 2, 5, 15, 30, and 60 min increments. Let each sample cool to room temperature before measuring.

Step (6) Analyze the results.

Here is a picture of each sample.  You can see the color of each test becoming more red with longer boiling times.  A picture of the color reference card that comes with the kit is also included:







Here is a graph of the results.   The NaNO2 was also calculated according to how much water was being lost to evaporation (Water volume before boiling:  1000ml.  Water volume after boiling for 60min:  250mL.  Evaporation rate:  12.5mL/min).  The two sets of results line up pretty close.







This test was a bit crude; but conclusive.
It was cheap, fun, quick, and interesting.  If you have high school/middle school aged kids, this might make a good science fair project.


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## JC in GB (Oct 14, 2019)

Thanks for that information.  When I read about NaNO2, I wondered the same thing.  According to the chemical makeup, NaNO2 won't break down until around 600 degrees F. 

My worry was that it may become more reactive as it heats and may combine with chlorine and other chemicals in the water.

Maybe I was just concerned over nothing...


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## dernektambura (Oct 14, 2019)

PolishDeli said:


> When mixing up a wet cure, some recipes say to use hot water to help the ingredients fully dissolve.  Other say not to use hot water because the sodium nitrite (NaNO2) in cure#1 breaks down when heated.
> 
> Over the weekend, I did some kitchen science experiments and concluded that it is safe to boil your brine.  The NaNO2 does not disappear, even if you boil the brine for over an hour. [NOTE: Whether you boil your brine or not, make sure to cool it down before immersing/injecting your meat!]
> 
> ...


Good read and excellent experiment... I think that cure#2 NaNo3 not suppose to be boiled cuz it will break down to NaNo2 + O2...


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## chef jimmyj (Oct 14, 2019)

Interesting to see these results. There are hundreds of posts here and on others sites and blogs, warning not to boil a Curing Brine. Well now one more thing not to worry about. Thanks...JJ


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## daveomak (Oct 15, 2019)

28.   (b) Raw Material Handling
29.   (i) Thawing must be monitored and controlled to ensure thoroughness and to prevent temperature abuse. Improperly thawed meat could cause insufficient cure penetration. Temperature abuse can cause spoilage or growth of pathogens.
30.   (ii) Meat must be fresh. Curing may not be used to salvage meat that has excessive bacterial growth or spoilage.

34.   (iii) Pieces must be prepared to uniform sizes to ensure uniform cure penetration. This is extremely critical for dry and immersion curing.

36.   (v) A schedule or recipe must be established for determining the exact amount of curing formulation to be used for a specified weight of meat or meat mixture.

37.   (vi) Methods and procedures must be strictly controlled to ensure uniform cure.

39.   (viii) All surfaces of meat must be rotated and rubbed at intervals of sufficient frequency to ensure cure penetration when a dry curing method is used.

40.   (ix) Immersion curing requires periodic mixing of the batch to facilitate uniform curing.

41.   (x) The application of salt during dry curing of muscle cuts requires that the temperature of the product be strictly controlled between 1.7°C (35°F) and 7.2°C (45°F). The lower temperature is set to limit microbial growth and the upper temperature is set for the purpose of ensuring cure penetration. Refer to USDA regulations 9 CFR 318.10(c)(3)(iv) for specific details on dry curing.

46.   (xv) Hot curing of bacon bellies, hams, or any other products must be performed at >49°C (120°F) as specified in 9 CFR 318.

Nitrite Dissipation from heat.....

Prague Powder #1
Also called Insta-Cure and Modern Cure. Cures are used to prevent meats from spoiling when being cooked or smoked at low temperatures (under 200 degrees F). This cure is 1 part sodium nitrite (6.25%) and 16 parts salt (93.75%) and are combined and crystallized to assure even distribution. As the meat temperate rises during processing, the sodium nitrite changes to nitric oxide and starts to ‘gas out’ at about 130 degrees F. After the smoking /cooking process is complete only about 10-20% of the original nitrite remains. As the product is stored and later reheated for consumption, the decline of nitrite continues. 4 ounces of Prague powder #1 is required to cure 100 lbs of meat. A more typical measurement for home use is 1 level tsp per 5 lbs of meat. Mix with cold water, then mix into meat like you would mix seasonings into meat. 

Prague Powder #2
Used to dry-cure products. Prague powder #2 is a mixture of 1 part sodium nitrite, .64 parts sodium nitrate and 16 parts salt. (1 oz. of sodium nitrite with .64 oz. of sodium nitrate to each lb. of salt.) It is primarily used in dry-curing Use with products that do not require cooking, smoking, or refrigeration. This cure, which is sodium nitrate, acts like a time release, slowly breaking down into sodium nitrite, then into nitric oxide. This allows you to dry cure products that take much longer to cure. A cure with sodium nitrite would dissipate too quickly. Use 1 oz. of cure for 25 lbs. of meat or 1 level teaspoon of cure for 5 lbs. of meat when mixing with meat. When using a cure in a brine solution, follow a recipe.


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## daveomak (Oct 15, 2019)

It appears, from test data, boiling water has no effect on nitrite in meats..  Frying, cooking etc. even storage has an effect on residual...
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4784486/

*Results*
The decrease in nitrite levels as a function of time after addition of NaNO2 to the meat products studied is shown in Figure 1. Already at 24 h after the addition of nitrite to lunch chicken sausage, grill chicken sausage, pork/beef sausage and liver paté, the nitrite levels had decreased to approximately 55%, 45%, 35% and 15% of the initial level, respectively. However, the decline in added nitrite was less pronounced in chicken sausage than in pork/beef sausage and liver paté, so that at the use-by date the nitrite levels were still approximately 40% in chicken lunch sausage and 15% in chicken grill sausage (Figure 1). A noteworthy feature was that the accepted storage period (until use-by date is reached) was almost twice as long for chicken sausage (48 days) as for pork/beef sausage (28 days). In fact, on applying the accepted period for chicken sausage, there was almost no nitrite left in the pork/beef sausage after 48 days.

*The results of the pilot study showed that boiling did not alter the residual nitrite level at all (data not shown)*. However, frying decreased the mean nitrite level from 11 to 5.6 mg kg–1, i.e., to approximately 50% of the initial level. This decrease did not appear to be related to the weight loss of the fried samples. Hence, it could be attributable to formation of unknown nitrogen-containing compounds, an issue that would require further research. The residual nitrite level in the assays was 11 mg kg−1 or less. Consequently, even though frying significantly affected the level of residual nitrite, it had a minor influence on the estimated total dietary intake of nitrite.


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## JC in GB (Oct 15, 2019)

daveomak said:


> It appears, from test data, boiling water has no effect on nitrite in meats..  Frying, cooking etc. even storage has an effect on residual...
> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4784486/
> 
> *The results of the pilot study showed that boiling did not alter the residual nitrite level at all (data not shown)*. However, frying decreased the mean nitrite level from 11 to 5.6 mg kg–1, i.e., to approximately 50% of the initial level. This decrease did not appear to be related to the weight loss of the fried samples. Hence, it could be attributable to formation of unknown nitrogen-containing compounds, an issue that would require further research. The residual nitrite level in the assays was 11 mg kg−1 or less. Consequently, even though frying significantly affected the level of residual nitrite, it had a minor influence on the estimated total dietary intake of nitrite.



Great information.  Is it possible that by frying the sausage in your example above that the missing nitrates are actually nitrosamines from the cooking process?

JC


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## PolishDeli (Oct 15, 2019)

dernektambura said:


> I think that cure#2 NaNo3 not suppose to be boiled cuz it will break down to NaNo2 + O2...


I’ll have to get a NaNO3 test kit, and repeat the experiment.
Thermodynamically though, NaNO3 is actually more stable than NaNO2.  (It has a lower Gibbs energy of formation).  So I don’t think breaking it apart into NaNO2+O2 would be a favorable reaction; and it’s why yeasts need to get involved during a slow cure process. I think.



JC in GB said:


> may combine with chlorine and other chemicals in the water


That’s a good thought, and why I’d like to test the stability in different acid strengths.  Though I suspect the color of the test will be affected by the acidity.  So interpretation of the results may be difficult.  Maybe this’ll be a future post…



daveomak said:


> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4784486/


Thanks for the literature.
I’m encouraged that my kitchen experiments are consistent with the results obtained by a real research team. 

Figure 1 in the Merino paper is interesting.  The drop in NaNO2 concentration for the different types of meats they tested tracks with the amount of heme iron in each of those meats. i.e., Liver has the most iron, so it converts the most amount of NaNO2.  Chicken the least.  Pretty cool, and makes perfect sense.

The effect of frying though..That's not obvious to me.  JC may be onto something.


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## daveomak (Oct 15, 2019)

JC in GB said:


> Great information.  Is it possible that by frying the sausage in your example above that the missing nitrates are actually nitrosamines from the cooking process?
> 
> JC



If you open the link, you will see hot the nitrite dissipates without additional processing...  It's not the frying process...  
I'm thinking they add ascorbic acid to speed up the curing process which immediately starts the break down on nitrite....


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## chef jimmyj (Oct 15, 2019)

An interesting side note for me, I've made hundreds of pounds of Liver Pate, from Duck, Chicken, Pork, Rabbit and Goose Foie Gras, and I  have never come across a recipe that used Cure #1. I will have to look into the Benefit and Flavor change, if any...JJ


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## JC in GB (Oct 15, 2019)

Just love exploring the science behind all this....


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## dernektambura (Oct 15, 2019)

PolishDeli said:


> I’ll have to get a NaNO3 test kit, and repeat the experiment.
> Thermodynamically though, NaNO3 is actually more stable than NaNO2.  (It has a lower Gibbs energy of formation).  So I don’t think breaking it apart into NaNO2+O2 would be a favorable reaction; and it’s why yeasts need to get involved during a slow cure process. I think.


Honestly I do trust everything you said cuz my chemistry level is still at very limited... Never fully understood math involving letters and numbers and mixing them together...
but I do know that for some chemical reason cure #2 NaNo3 has to be mixed in cold brine.. Now, how does it 1% nitrate turns in to dissipated nitrite over time is mistery to me...
and I do know for fact that if you use cure #2, then it is no need for yeast and vice versa....


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## daveomak (Oct 16, 2019)

dernektambura said:


> *and I do know for fact that if you use cure #2, then it is no need for yeast and vice versa*....



Would you explain that ...  Are you saying ...  "*If you use yeast, there is no need for cure#2*"


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## dernektambura (Oct 16, 2019)

Sausages: if you use yeast for flavouring + fighting of bad bacteria you can go by with cure#1....
Dry aged meat doesn't need yeast flavouring so no need for yeast and you use cure#2...


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## chef jimmyj (Oct 16, 2019)

Ground Meat Dry Sausages need BOTH Cure #2 to give long term, several months, protection against Clostridium Botulinum growth in the oxygen free inner portion of the sausage, commonly aged at 55-65°F. And a Bacterial Starter Culture to Acidify the meat. The Low pH inhibits other harmful bacteria, Listeria, and Spoilage bacteria.
I am currently unaware of any type of Yeast used in Dry Sausage Curing. That's not to say there aren't any...JJ

From Meats and Sausages
*Culture name*
F-LC
*Bacteria included*
 Staphylococcus xylosus,
Pediococcus acidilactici,
Lactobacillus curvatus
*Characteristics
Culture* for acidification and prevention of Listeria.


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## dernektambura (Oct 16, 2019)

chef jimmyj said:


> Ground Meat Dry Sausages need BOTH Cure #2 to give long term, several months, protection against Clostridium Botulinum growth in the oxygen free inner portion of the sausage, commonly aged at 55-65°F. And a Bacterial Starter Culture to Acidify the meat. The Low pH inhibits other harmful bacteria, Listeria, and Spoilage bacteria.
> I am currently unaware of any type of Yeast used in Dry Sausage Curing. That's not to say there aren't any...JJ
> 
> From Meats and Sausages
> ...


Now a days everybody use nitrite for long term shelf stability... but not that long ago ((50yrs), non comercial production at home of long term shelf stability products were achieved by using only salt and cold smoke... sausages and meat were saltier...


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## PolishDeli (Oct 16, 2019)

I was wrong to use the word “yeast”
As pointed out by JJ, it’s lactic acid producing bacteria, not yeast, that is in starter cultures.

My understanding of the curing process is that NaNO3 is reduced to NaNO2 by microorganisms.  Then NaNO2 is reduced to NO which binds to heme iron in myoglobin.

The reaction 2NaNO3->2NaNO2+O2 will happen with heat; but at ~400°C.

I think the idea that NaNO3 breaks down in boiling water comes from an incomplete account of research which reports that NaNO3 concentrations decrease in boiled vegetables.

For example; this from Marianski:  “Cooking by boiling reduced Nitrate concentrations in most of the vegetables”

However, Fletcher et. al. tell a more complete story:
“The effects on the nitrate content of vegetables exposed to boiling in water for various lengths of time is described. Whilst certain cultivars show a steady decrease in nitrate levels, other varieties show an initial rise. *The nitrate content of the cooking water used shows a sustained increase as the cooking time is extended*.” (DOI: 10.1177/026010608700500209)


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## chef jimmyj (Oct 16, 2019)

dernektambura said:


> Now a days everybody use nitrite for long term shelf stability... but not that long ago ((50yrs), non comercial production at home of long term shelf stability products were achieved by using only salt and cold smoke... sausages and meat were saltier...



You are mostly correct and a good observation. However, while it's true that the use of only Salt and Smoke, or even just Salt, the production of Prosciutto, is thousands of years old and continues in some forms today. The invention and use of Sodium Nitrite in the form of Prague Powder, aka Cure #1, can be traced back the to mid 1800's in and around Prague in the Austro-Hungarian Empire under the rule of the Habsburgs.
Both of my Grandfather's used Cure #1 to cure Kielbasa and Bacon a Hundred years ago...JJ


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## dernektambura (Oct 16, 2019)

True but Prague powder wasn't widely used up until mid of the 1900... before mid of 1900, Europe was 85% rural and only place you could find prague powder was in drug stores and only by order, meaning, pharmacist had to mix it for you... mass production of prague powder wasn't available for long time.... out of 85% of rural population, only 15% could read and I doubt it they read about prague powder.... that kind of info wasn't available as today and most of people were suspicious about anything new and progresive... my grandpa died back in 1980's and never used anything but salt...


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## daveomak (Oct 17, 2019)

The salt used in Europe way back when, had naturally occurring nitrates...  which controlled and killed botulism bacteria...  The salt, removed moisture from the meat which controlled other bacteria etc....


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## dernektambura (Oct 17, 2019)

I thought that most of nitrite way back in the early 1800's came from Chile... In europe there is no significant deposits of saltpetre for example... finally at turn of 19th century and before WWI germans came up with way to make synthetics nitrite which they used in production of explosives ...


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## PolishDeli (Oct 17, 2019)

According to Herrador et al. (2005), Mediterranean sea salt contains 1.2 ppm NaNO2 and 1.1ppm NaNO3:

“Como sea, los resultados obtenidos indicant un contenido de 1.2 y 1.1 mg/kg de nitritos y nitratos, respectivamenta…”


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## daveomak (Oct 17, 2019)

Updated April 24, 2017
By Kelly Wallace
Also known as saltpeter, potassium nitrate is a white crystallized compound composed of potassium, nitrogen and oxygen. Most commonly used in fireworks, matches and fertilizer, its medical applications include diuretics to reduce high blood pressure. Although typically produced synthetically, mining continues of the natural mineral, which has significant commercial value.

*History and Use*
The use of potassium nitrate goes back to the early Romans and Greeks, who used saltpeter to fertilize their plants. In the third century B.C., the Chinese learned that a mixture of charcoal, sulfur and potassium nitrate could create an explosive powder. Since the Middle Ages, it has played a role in preserving meat and tanning hides, as well as glass production and metalworking. Modern uses include gunpowder, food preservatives, various crafts and to lessen angina pain in heart patients.

*Formation*
Potassium nitrate forms naturally in warm climates. Bacteria from the decomposition of feces, urine and plants combine with air, moisture, plant ash and alkaline soil to create nitrification—the conversion of the decaying matter into nitrates that penetrate the soil. Dissolved by rainwater, the evaporated deposits form a white powder. Once boiling and evaporating wash impurities away, potassium nitrate is ready for practical uses.

*Cave Deposits*
In the early part of the 19th century and throughout the Civil War, caves in many Southern states were rich sources of potassium nitrate. Usually found as huge crusts and growths on cave walls and ceilings, they formed when solutions containing alkali potassium and nitrate seeped into cavern cracks and crevices. For example, the DesertUSA website reports that miners extracted 200 tons of potassium nitrate from Mammoth Cave in Kentucky between 1811 and 1814, to use in the making of gunpowder.

*Limestone Caves*
Crystallized deposits of saltpeter occur in limestone caves that house bats or other creatures. A process of nitrification starts when the animal droppings come into contact with the limestone. The resulting nitrate compound dissolves in rainwater and falls to the ground where it evaporates, leaving a salt. Such caves are in Italy, the United States (Tennessee and Kentucky) and Africa.

*Soil*
Saltpeter occurs as crystalline veins in soil in the Ganges Valley of India and as fluorescence on the soil in parts of Indonesia. It is gathered by dissolving the salt in water and evaporating the solution to obtain a salt.

*More About Nitrates *
Rock salts were mined in different areas of the world and exhibited different properties which depended mainly on impurities contained within. Take for example Himalayan salt that is sold on the Internet for cooking - it is pink. In the past when we used salt with a higher potassium Nitrate content, we discovered that the meat had a different taste and color. Potassium Nitrate was the main ingredient for making gun powder and it’s commercial name was saltpeter, still used today. Potassium Nitrate (KNO3-Bengal saltpetre) or sodium Nitrate (NaNO3- Chile saltpetre) were even added to water causing the temperature to drop and that method was used to cool wine in the XVI century. Nitrates and nitrites are powerful poisons and that is why the Food and Drug Administration established limits for their use. So why do we use them? The simple answer is that after testing and experiments, our modern science has not come up with a better solution to cure meats and prevent food poisoning. Only in the XIX century a German fellow Justinus Kemer linked food poisoning to contaminated sausages. It took another 80 years to discover botulinum bacteria by Emile Pierre van Ermengem, Professor of bacteriology at the University of Ghent in 1895. The first scientific papers that explained the behavior of Nitrates were published only in the XX century so why had we been using Nitrates so much? Not to prevent botulism of which we had never even heard of before. We had been and still are using Nitrates because: Nitrates can preserve meat’s natural color. The same piece of ham when roasted will have a light brown color and is known as roasted leg of pork. Add some nitrates to it, cook it and it becomes ham with its characteristic flavor and pink color. Nitrates impart a characteristic cured flavor to meat. Nitrates prevent the transformation of botulinum spores into toxins thus eliminating the possibility of food poisoning. Nitrates prevent rancidity of fats.

Marianski, Stanley. Home Production of Quality Meats and Sausages (Kindle Locations 747-765). Bookmagic LLC. Kindle Edition.


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## dernektambura (Oct 17, 2019)

PolishDeli said:


> According to Herrador et al. (2005), Mediterranean sea salt contains 1.2 ppm NaNO2 and 1.1ppm NaNO3:
> 
> “Como sea, los resultados obtenidos indicant un contenido de 1.2 y 1.1 mg/kg de nitritos y nitratos, respectivamenta…”


That comes out to about 200 times less than max ppm for now a days cure for meat and about 120 times less for bacon...


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## indaswamp (Dec 24, 2020)

dernektambura said:


> Honestly I do trust everything you said cuz my chemistry level is still at very limited... Never fully understood math involving letters and numbers and mixing them together...
> but I do know that for some chemical reason cure #2 NaNo3 has to be mixed in cold brine.. Now, how does it 1% nitrate turns in to dissipated nitrite over time is mistery to me...
> and I do know for fact that if you use cure #2, then it is no need for yeast and vice versa....


Staphylococcus strains are responsible for the conversion of nitrate to nitrite in dry cured meats...
@6 minute mark...


Can also be found digging through Chr Hansen literature.


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## indaswamp (Dec 24, 2020)

chef jimmyj said:


> I am currently unaware of any type of Yeast used in Dry Sausage Curing. That's not to say there aren't any...JJ


Debaryomyces Hansenii...

https://www.sciencedirect.com/topics/immunology-and-microbiology/debaryomyces-hansenii
One that I know of....I am sure there are more that we don't know of that play a role when curing salami...


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## bill ace 350 (Dec 31, 2020)

PolishDeli said:


> When mixing up a wet cure, some recipes say to use hot water to help the ingredients fully dissolve.  Other say not to use hot water because the sodium nitrite (NaNO2) in cure#1 breaks down when heated.
> 
> Over the weekend, I did some kitchen science experiments and concluded that it is safe to boil your brine.  The NaNO2 does not disappear, even if you boil the brine for over an hour. [NOTE: Whether you boil your brine or not, make sure to cool it down before immersing/injecting your meat!]
> 
> ...


Very interesting. Glad i came across this.

Refreshing to see something other than the typical copy and paste of information.


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