The Science Of Curing Meats Safely
"I like to say there should be no rules in the bedroom or kitchen. The exception is curing meats. The rules for this process are rigid." Meathead
You must read this before curing meats
Curing involves using the preservatives sodium nitrite and nitrate. If you do it wrong you can make someone sick. But getting it right is not hard. My recipes are carefully calculated to be safe. Please do them exactly as published. If you must scale the recipe up or down you cannot simply multiply the ingredients. You must use our special curing calculator below.
I cannot and will not comment on recipes from other websites or variations you want to try. You should not try to combine my curing recipes with others. There is a lot of misinformation out there. If you failed to follow my directions, please don't ask me how to fix your meat. Sorry to be so pedantic. If you know this website, we encourage experimentation on normal recipes. But you should not experiment with recipes using nitrites. Remember, when in doubt, throw it out.
The importance of nitrites
Curing meat is a preservation process going way back to ancient civilizations long before refrigeration. Probably some primitive tribe discovered that a dead animal washed ashore hadn't rotted, and although the meat was salty and gray, it was still tasty and nobody died. Then they started experimenting, and along the way they killed a few kinfolk, but eventually they figured out how to preserve meat with salt.
Then, probably in the 1600s, somebody discovered that a mix of salt and saltpeter, when rubbed into meat, worked better. They didn't know it, but the potassium nitrate in saltpeter kills Clostridium botulinum, the deadly bacterium that causes botulism. The nitrate also preserved the pink color of the meat.
Today hardly anybody uses saltpeter and neither should you. Specially prepared blends of salt, sodium nitrite, and sodium nitrate are used by commercial producers and home cooks alike. Called curing salts as a group, they are why bacon, hot dogs, hams, and corned beef are pink and why they have a distinctive tangy cured meat flavor.
Individually they are named Prague Powder #1 (a.k.a. Insta Cure #1 or Pink curing salt #1), Prague powder #2 (a.k.a. Pink curing salt #2), Insta Cure #2, Morton Tender Quick, and good old Saltpeter. All my recipes use Prague Powder #1 which has only sodium nitrite, no sodium nitrate. Sodium nitrate is sometimes used on meats that age because it slowly breaks down into sodium nitrite over time so it remains active over months. But nitrates can also form nitrosamines, a compound that is a carcinogen in animals, but its effect on humans is still ill defined. Unless you are an expert, you should never substitute one curing salt for another. I describe them in detail in my article on the Science of Salt.
Nitrites, botulism, and safety
The idea that nitrites or nitrates were carcinogenic was the result of a flawed experiment in the 1970s and, although it has been debunked, the bad reputation won't go away. In 2003 the World Health Organization flat out said it: "No association was found with oral, oesophageal, gastric, or testicular cancer." Research shows that about 95% of the nitrites we consume come from the natural compounds in vegetables such as lettuce, spinach, celery, and carrots, and even some drinking water. Click this link for more on the subject.
The AmazingRibs.com science advisor Prof. Greg Blonder explains that "Children and pets are much more sensitive to nitrites, and infants even more so. They lack certain enzymes and their digestive tracts harbor bacteria that convert nitrate in veggies into nitrite. This is why commercial baby food is designed to be low nitrite/nitrate, and why some parents who make their own natural baby food from spinach can actually harm a young child because spinach is high in nitrite." For this reason you must store curing salts where children cannot get into them.
Clostridium botulinum is a curious and dangerous beast. It is the single most deadly food pathogen, far more deadly than pathogenic strains of E-coli or salmonella. Bot doesn't grow well in the presence of air, so it forms tough shell-like spores and hibernates until conditions are right. The spores are commonly found in the environment all around you.
But they are not a problem unless conditions allow the spores to germinate and produce deadly botulinum toxin. Clostridium botulinum prefers anaerobic (oxygen free) conditions. So submerging meat in water for days is rolling out the welcome mat. And cooking the meat when it comes out is no guarantee of safety because the spores don't start croaking til the temp hits 250°F or so. So boiling water won't get them since it never gets above 212°F.
As scary as all this sounds, the good news is that the Clostridium botulinum that emerge from spores are much more sensitive and they die at about 175°F and the toxins they produce are inactivated at about 160°F. You might ask, why not dry cure, in air rather than in water, but there is little oxygen deep in the center of a slab of meat, so Clostridium botulinum spores can hide and grow there.
It is widely believed that USDA has set the limit of 200 ppm for cured meats, but this is a myth. USDA has established regulatory limits for the addition of sodium nitrite at 120 ppm (0.012%) in wet cured bacon, 200 ppm (0.02%) for dry cured bacon, 156 ppm (0.0156%) for products such as frankfurters or cured sausages, 200 ppm (0.02%) in wet cured or injected products such as ham or pastrami, and up to 625 ppm (0.0625%) of sodium nitrite in dry-cured meat products such as country hams.
USDA also requires 550 ppm (0.055%) of sodium ascorbate or sodium erythorbate to be added in commercial bacon production. This increases nitric oxide formation and, as we explain in our article on the smoke ring, NO is what gives cured meats their pink color when it combines with the protein myoglobin. It also greatly reduces or prevents the formation of nitrosamines. Our recipes do not require these extra additives, so it is considered safe, even desirable, to use the 200 ppm as a maximum target. Prof. Blonder, has written about the subject of nitrite toxicity in detail here. I have written about nitrites and nitrates and the cancer scare of the 1970s here.
People often ask if they can cure meats without nitrites and just increase the salt. Salt inhibits bot's growth, but won't kill it. Neither will vinegar. You should not attempt to cure meat at home without a curing salt.
There are some "natural" or "no nitrite" cured meats on the market, but if you look closely at the label, they often have some sort of extract of celery in them because it contains nitrate which can convert to nitrite. There are recipes for "curing" that don't use nitrites, so technically they are not really cures, and they cannot kill bot so they must never be submerged in wet cures. I consider them risky.
That's why you must resist the temptation to improvise in a few key areas. But if you stick to my recipes, you can make absolutely mindblowing pastrami, bacon, and more. I'll discuss below where you can improvise.
Three common curing methods
In the days before refrigeration, cured meats were heavily salted, treated with saltpeter, smoked, and often hung in cool cellars. The salt, saltpeter, and smoke concentrations were inconsistent and the meats often dehydrated and grew molds as they hung. These methods have been perfected and the meats are highly prized.
The problem is that in order to do this properly you need a great deal of expertise and you should have precise thermometers, scales, measuring tools, refrigeration, and you must maintain excellent sanitation. Don't let anybody bamboozle you, even the most ancient tradition-bound old world producers are government inspected and use modern instruments to make sure they pass. The shop in Rome shown here is full of cool looking artisinal cured moldy meats that have all been properly produced.
Today there are three common methods of curing meat: Injecting, dry curing, and wet curing.
Injecting is done for most inexpensive hams, corned beef, and bacon. The meat is passed through a machine with scores of needles that stab it and inject a precise amount of curing solution. It is fast and cheap with little waste. But it tends to pump a lot of water into the meat diluting its flavor. It can be done at home, but it is tricky to get the right amount of salt and cure in there. One of the problems is that a single needle injector tends to create pockets of cure and pockets of no cure. And it doesn't treat the surface with flavor. Tools and techniques for injecting here.
Injection curing should be left for the pros.
Dry curing is how they make prosciutto, Iberico ham, Serrano ham, and American Country ham. To dry cure, you mix up your salt and spice mix, coat the meat, and store it in a temperature and humidity controlled space. Dry curing is slow. Simple bacon can take a week and large meats like hams can take months. Dry curing requires a lot of space to hold the meat, and ties up inventory for far longer than most businesses like. The energy costs can also be burdensome. In dry curing, if you can't control humidity, temp, or salt precisely, you invite bacteria and mold. Some are beneficial. Some are deadly. Before you undertake dry curing, you should be able to tell which is which. That means a good microscope, and anlytical tools. The long curing process often results in oxidized rancid fat, a funky flavor that, like funky cheese, some people love and some people hate.
Dry curing should be left for licensed pros.
Wet curing means submerging the meat in a chilled liquid with nitrites and/or nitrates and flavorings. The cure dissolves and disperses in the lquid and the liquid has a uniform concentration of cure throughout as long as it is stirred occasionally. Because the meat is about 70% water, the cure tries to achieve equilibrium with the liquid in the meat. Wet curing takes less time than dry curing, sometimes only days. On a commercial scale, it requires a lot of space and cooling.
If you are doing only a small amount at home, it is by far the best way to go.
Why I recommend wet cures
The science of curing is pretty cool. Meat is really a protein and fat sponge that is about 70% water (see my article on meat science). Salt draws water out of the meat, concentrating its flavor and making it less hospitable to microbes. It also draws moisture out of bacteria, killing them. Salt also slows oxidation of the meat so the fat doesn't go rancid quickly.
But salt also penetrates meat. Salt (NaCl) is a very tiny molecule with only two atoms, a sodium (Na) and a chloride (Cl). It easily splits into sodium and chlorine ions when it gets wet and they get electrified and easily penetrate the pores and membranes.
Nitrite is also a small molecule, NO2, three atoms, one nitrogen (N) and two oxygens (O). Nitrite breaks down into nitric oxide (NO) and binds to the iron atom (Fe) in myoglobin in the meat. Myoglobin is the protein that gives meat its red color. The chemical process is similar to the process that causes the pink smoke ring in smoked meats and it gives cured meat its characteristic pink color.
I prefer wet cures because submerging the meat in liquid makes it easier to control the amount of salt in the meat. The salt concentration for wet curing is higher than the typical 4 to 6% brine used to moisten chicken, turkey, and pork before cooking. Nature seeks equilibrium, so it tries to make the salt concentration inside the meat the same as outside. So the trick is to create a cure that has the right amount of nitrite and liquid so that the nitrite will penetrate all the way to the center of the meat, preserve the meat, and fight off bacteria without allowing it to suck in too much salt or too much nitrite. Wet curing also prevents "hot spots" where there is more cure in one spot than in other spots, a problem in dry curing, and wet curing won't make thin areas saltier than thick areas. When submerged in a wet cure, the salt concentration is the same all around the surface and the laws of equilibrium keep the meat the same salinity throughout if you keep it in the cure long enough. In a wet cure the humidity is more easily controlled than in a dry cure, it is always 100%. Wet cures also hide the meat from oxygen, inhibiting most bacteria and preventing rancidity. So making the process anaerobic protects you from all the bad guys except bot, and the nitrite knocks bot out.
One problem with dry cures is that you need to put it on a rack or hang it in the fridge so air can flow around it.
And yes, I know my endorsement of wet cures seems to contradict my love of dry brining other meats like steak, chicken, and pork. But with those meats you are applying only plain salt, not a curing salt, you are applying it a short time before cooking, and you are using salt in smaller quantities just to amplify flavor. This is a vastly different chemical process.
All this said, there is one important argument in favor of dry curing. It encourages growth of some bacteria and molds that, if you know exactly what you're doing, can produce interesting flavors and complexity, especially in hams. That's one reason why prosciutto is so expensive. In this picture you see an expert at Prosiuittificio Ghirardi Onesto in Parma, Italy. He uses a thin sharp bone and sticks it in every single ham that is aging in their temperature controlled cellar, and then sniffs the bone to make sure everything is proceeding according to plan.
Why I recommend Prague Powder #1
All my recipes use Prague Powder #1, the most common curing salt. It is approximately 94% plain old salt with approximately 6% sodium nitrite, some anticaking agents, and a tiny bit of red dye. The red dye is not for the meat, it turns the salt pink so you don't mistake it for regular salt or sugar in your pantry. It is not the same thing as Himalayan pink salt or Prague Powder #2. Prague Powder #2 and some other curing salts contain nitrates (with an a) which can form nitrosamines which can be carcinogenic under sertain circumstances. It's not easy to find Prague Powder #1 in groceries, but butcher shops, sporting goods stores where they sell sausage making gear, and Amazon.com carry it. Just click the link. If you can't get it, don't substitute.
Why I recommend Morton's kosher salt
Table salt contains some additives that we don't need, so I recommend Morton's kosher salt because it is purer. But, as I explain in my article on salt, the grain size and the air spaces between the grains plays an important role in the salinity, or the quantity of NaCl. A teaspoon of table salt contains almost twice as much NaCl than a teaspoon of Morton's Kosher Salt because it is smaller grain and tighter packed. Since salinity is a key part of these recipes, I have standardized on the most common kosher salt, Morton's. Diamond Crystal and other brands are different salinity by volume and will not work in my recipes. Don't tell me you can't find Morton's. It should be in every grocery store. If you insist on another salt you must alter the quantity. Use the conversions in my article on salt.
Why I recommend hot smoking
There are many recipes for cold smoking meat. In them you heat the meat very little and just flavor it with cold smoke. This is risky and I have written about the dangers at length in an article on cold smoking. All my recipes call for cooking the meat at temperatures of about 225°F to an internal temp of between 145 to 165°F. This pasteurizes the meat. Again, this is a safety step. Hot smoking is easy to do at home, and makes great tasting bacon, ham, corned beef, etc. They will keep for a week or two in the fridge and they freeze beautifully for a month or more.
Why I recommend distilled water
Tap water is almost always safe to drink, but it is never pure. It usually has small quantities of microbial and chemical contamination. Please use distilled water if the recipe calls for it. It is widely available in drug stores and many groceries. Some cooks go so far as to mix the curing liquid, bring it to a boil to decontaminate the salt, sugar, etc., and pour the hot water into the curing vessel to pasteurize it. After the curing solution cools, then the meat goes in. If you absolutely refuse to buy distilled water, then you can use other water but you must bring it to a hard boil for a few minutes and then let it cool thoroughly before the meat or nitrite go in.
Cleanliness is crucial
You must make sure the container the meat will be in is superclean. It must be non-reactive meaning it must be food grade plastic, glass, stainless, porcelain. Aluminum, cast iron, brass, and copper pots can undergo a reaction with chemicals in food, especially acids and salts, and create off flavors.
Scrub it with hot water and soap, and then thoroughly rinse out the soap. Then mix one ounce of household bleach to a gallon of water and rinse out the container with that. Let it sit for 10 to 15 minutes or so. Then rinse thoroughly and dry with paper towels. The bleach will kill bacteria and the rinse and dry will remove any traces of bleach. Some people use Star San, a solution popular with brewers.
You also need to scrub the meat with warm water. Normally we tell you that washing meat is not necessary and even risky because you can create invisible aerosols of bacteria in the washing process and the contaminents get all over the sink, faucet, dish drain, and counter surfaces. It is usually unnecessary because you are about to cook the chicken and the high heat will pasteurize it immediately. But when you are curing meat, you are submerging it in water for days, so you want to get off as much of the flora on the surface as possible. You'll never get it all, but get as much as you can.
CDC (Centers for Disease Control and Prevention) says the maximum safe daily intake of sodium nitrite is about 0.1 milligram (mg) per kilogram (kg) of your body weight. That means about 7 mg of pure sodium nitrite for a 150 pound person. But we don't (and shouldn't) eat pure sodium nitrite. Instead, it is mixed into our cured meats. FDA regulations limit sodium nitrite (NaNO2) to less than 200 ppm (parts per million) in foods, and hope a balanced diet will assure the average daily intake is below the CDC regulations.
The fact is that there is some uncertainty about this number because scientists can't give nitrites to people in large doses and wait to see what dose kills them or makes them sick. When we make cured meat we shoot for less than the 200 ppm number, but the fact is that nitrite is rapidly converted to nitric oxide (NO) during the cure so the actual amount is likely to be less. In addition, during the smoking process a substantial amount can drip away as heat shrinks the meat.
According to Prof. Greg Blonder, the AmazingRibs.com science advisor, while sodium nitrite is very dangerous ingested in its pure form, once absorbed by the meat it converts to nitric oxide and then bonds with the meat's myoglobin. Very little remains active. To obtain a lethal dose, a 150 pound person would have to consume in one sitting about 175 pounds of cured meat containing 200 ppm sodium nitrite, more than his or her body weight! Even if you could eat that much, salt, not nitrite, probably would be the killer. Still, it is important, when you make your own cured meats, that you stay within safe limits because everyone's tolerance is different, especially old, young, frail, or immune compromised people. A few slices of cured meat on a sandwich every day, and a ham for Sunday dinner can't hurt you.
In our cure recipes, we make sure you are well within safe limits. In our wet cured ham recipe for example, we add 3 tablespoons of Prague Powder #1 to 3 gallons of water. One tablespoon contains 18 gm of curing salt, but Prague Powder #1 is 6% sodium nitrite. 3 gallons of water weighs 11 kg, so the cure has an equivalent 100 ppm Prague Powder #1, well within the safe zone. And remember, chemical reactions during the curing process and drip loss during cooking significantly reduce the dose. For more on the topic, here is an article by Prof. Blonder.
Some helpful numbers (rounded)
- Government regulations limit sodium nitrite (NaNO2) to less than 200 ppm (parts per million) in foods
- Prague Powder #1 = 6% sodium nitrite (NaNO2) + 94% salt (NaCl)
- 1 tablespoon Prague Powder #1 weighs ≈ 13.2 grams and contains 0.8 gm sodium nitrite
- 1 tablespoon Prague Powder #1 mixed with 1.5 gallons water ≈ 200 ppm
- 1 teaspoon Prague Powder #1 mixed with 1/2 gallon water (8 cups) ≈ 200 ppm
- 1 gallon of water weighs ≈ 3.66 kg
The recipes on this site are properly formulated. But scaling up or down is tricky. To get the right amounts for them you must use Prof. Blonder's Wet Curing Calculator, below.
It is essential that you remember, that all our recipes and that this calculator are for wet cures. You may see other recipes out there but if they are for dry cures there is no comparison (read the rest of this page to understand the diff). Yes, I know there is another curing calculator out there on the interwebs but there is no author listed, the page has many broken links and graphics, the parent site appears to be abandoned, and it includes sugar and plain salt which are not critical parts of the cure, they are mostly flavorings. Please don't ask me about differences between that calculator and the one below written exclusively for this site by Prof. Greg Blonder, an eminent physicist, engineer, and food scientist.
Note: Blonder has rounded some numbers to make the measurements easier to work with and because the weight of Prague Powder #1 can vary depending on humidity, how tightly you pack the measuring spoon, the meat fat content, pH, and thickness. But if you aim for 150 ppm and end up 2x higher or lower, it will still be safe to consume after cooking. Let us know how the calculator's time estimate works for you (make sure to let us know all the conditions).
Prof. Blonder's Wet Curing Calculator Version 2.0Step 1 - Scaling all ingredients except Prague Powder #1. If the recipe is for 3 pounds and you are making 6 pounds, multiply all ingredients except Prague Powder #1 by 2. This calculator will tell you how much Prague Powder #1 to use and how long to leave it in the liquid in the yellow boxes below. Pay close attention your data entry so you don't make a mistake.
|Step 2 - Cure Level. Enter a cure level by moving the slider. We recommend 150 ppm of sodium nitrite but just about any number between 100 and 200 will work. 200 ppm is the maximum recommended by food safety experts, a conservative number, and you can go over a bit because there is drip loss during cooking, but you should play by the rules to be safe.|
|Step 3 - Meat Weight. Enter the weight of the trimmed meat after you have removed all skin and surface fat. If you are doing brisket we strongly recommend you separate point from flat and remove the fat layer between them. Use decimal equivalents for fractions (enter 3.5 not 3 1/2).|
|Step 4 - Liquids. Enter the amount of liquid in the original recipe times the amount you are multiplying the recipe by. If there are other liquids in addition to water such as maple syrup or sriracha, be sure to include them in your liquid totals. Note that our bacon recipes are designed to use less liquid than normal but don't worry, they still work. Use decimal equivalents for fractions (3.5 not 3 1/2).|
|Step 5 - Prague Powder #1 Calculation. The calculator will tell you how much Prague Powder #1 to use. Remember, it is not a multiple of the amount of meat. It is calculated based upon the variables you entered in Steps 1 through 3. Try to get pretty close to this amount.|
|Step 6 - Meat thickness. Measure the thickness of the thickest part.|
|Step 7 - Meat Shape. Select the appropriate shape: Flat is like a pork belly, tube is like a pork loin, and cone is like a ham.|
|Step 8 - Minimum Time In Cure Calculation. The calculator will tell you how long to leave the meat in the cure. You can go 25% longer than the minimum time if you wish, but don't push it any more. Don't go shorter or you may have uncured meat in the center. Curing time also depends on the cut of meat, how much fat covers the surface, and the species. Keep meat in the cure in a refrigerator between 34 and 38°F (1 to 3°C). This is the ideal fridge temp anyway.|
|Copyright © 2016 by AmazingRibs.com. Created by the AmazingRibs.com Science Advisor, Prof. Greg Blonder. Contact Meathead for permission to use it on your blog or website. This is version 2.0.|
Do not stack meat!
As the thickness of the meat increases you need both more time and more cure. A rule of thumb is that the salt will move at about 1/4" per day, but that can vary depending on temp, fat content, and total thickness (it moves slower the deeper it gets).
If the recipe calls for eight pounds of brisket and you have two four pound hunks, if you stack them on top of each other you have made it twice the thickness. There is little cure between the slabs, so the recipe will not work. The salt might not reach the center in the recommended time. And while it is in the cure, stir it around daily so any meat in contact with the container will get exposed to the cure.
If you use a zipper bag, flip it and squish the liquid around to make sure all surfaces are in contact with it. If you use a pan, hold the meat under water with a plate or another weight. If it is in contact with the bottom, flip it regularly.
Where you can improvise
Most cures are mixed with salt, sugar, and spices. Other than salt and nitrite, very little else added to a cure will penetrate deep into the meat. The molecules are just too large. They remain on and near the surface. I discuss this phenomenon in my article on marinades. Adding more or less sugar, spice, and everything nice only impacts taste on the surface, not safety, so you have room here to improvise. You can swap fruit juice for water if you want. But remember the ratios of nitrite and water are crucial, so don't increase the liquid content without increasing the other proportionally as per the conversion tables. If you are diabetic, you can easily skip the sugar although very little remains on the surface. But keep in mind, things like maple syrup in my bacon recipe are not just a sweetener, they are the water, too! As always, please stick to my formula.
Here's what a slab of my bacon looks like after my wet cure before smoking. The black spots are pepper and they are all on the surface.
Weirdness and troubleshooting
After a week in the cure, beef may look a little gray on the outside but stay pink in the center. That's because oxygen has impacted the surface while the nitrites have fixed the myoglobin. Some fats may get gelatinous, particularly on ham. The water may get a little pink from myoglobin being pulled out, but it should remain transparent and never be cloudy. Bits of fat may break loose and float, but floating mold is a bad sign. Bubbles are a sure sign that something is alive in there. It should always smell fresh, perhaps a little briny, but never funky. When in doubt, throw it out!
The bottom line
Read my article on the Science of Salt.
Use only Prague powder #1. Do not substitute saltpeter, Tenderquick, Himalayan pink salt, or Prague powder #2.
Use Prof. Blonder's Wet Curing Calculator above is you want to make more or less meat.
Do not dry cure.
Do not stack slabs of meat. Be aware of thickness.
Do not use a batch of cure more than once.
Sanitation is crucial. Your containers must be rated "food safe", clean, and non-reactive.
Use distilled water or boil your water and let it cool.
Keep the meat submerged. If necessary put a non-reactive weight like a dinner plate on top of it.
You must keep the meat between 34 and 38°F which is ideal refrigerator temp.
Do not mix my recipes with others.
When in doubt, throw it out! Don't take risks with meat. Even though you might cook it well past the safe temp of 165°F, botulism spores can survive to higher temps!