From the hills of Italy to the Spanish plains, dry-cured pork has been an essential (and delicious) food source for many cultures. In Dry-Curing Pork (The Countryman Press, 2014), Hector Kent explains the techniques and traditions of dry-curing in clear and accessible language. This excerpt, which explains the basics of the dry-curing process, is from the Section, "The Art of Dry-Cured Meat."
The application of salt to meat is the first critical component of dry-cured meats. Salting also includes the addition of nitrates and nitrites, if used.
When people ask what dry-cured pork is, I describe it as “salty, old meat”—a description that not everyone sees as favorable, but I find efficient and accurate, as you can’t have dry-cured meat without salt and age. Salt both prevents the growth of unwanted bacteria, and aids in the drying of the meat.
Embrace the saltiness of dry-cured meats, and if you’re trying to limit salt in your diet, slice the meat thinly, and consume in moderation. There is a small range of adjustment to salt concentration you can make in the recipes, but as with all preserved foods, important and inflexible guidelines dictate the amount of salt. The recommended guideline is more than 2.6 percent salt in all dry-curing, and 0.25 percent curing salt.
Salt is a primary ingredient and flavor, and using an interesting sea salt will add complexity to your finished product. The different mineral profiles found in sea salts will influence flavor in different ways, so as you refine your recipes, I encourage experimentation with different types of salt. Be aware that some salts contain many impurities, which may remain on the outside of the meat after the salt has been absorbed; just rinse them off, and they shouldn’t be a concern.
An alternative to sea salt is Diamond kosher salt, which has a relatively neutral flavor and is inexpensive, easily available, and recommended by many professionals. I often use the brand and I’ve always been pleased with the results. Unlike Morton kosher salt (which will also work well), Diamond kosher doesn’t contain any anti-caking agents. If it isn’t available, canning salt is also a pure salt option. Do not use iodized table salt.
Few ingredients in our food are so ubiquitous yet so maligned as nitrates and nitrites. Commonly referred to as curing salt, and naturally occurring throughout the biological world, including in the human body, nitrates, nitrites, and their related nitrogen-based compounds are among the basic components of the world’s nutrient cycles (remember the nitrogen cycle from middle school?). They are critical for our world’s functioning ecosystem, and are essential for the safety of many dry-cured meats.
In dry-cured meats, nitrates, nitrites, and their intermediate compounds are responsible for the flavor, color, and, most important, safety of the meat, from the finest Spanish jamon to the lowly gas station meat stick. Regardless of all the other benefits, the fact that curing salt is 100 percent effective in preventing botulism is enough of a reason to include it in all of these recipes.
Curing salt is purchased in a form that resembles standard table salt; it always contains nitrites, and sometimes nitrates. Curing salt is toxic in large quantities, so it is critical to keep it well labeled and out of reach of children. The quantity of curing salt used in all this book’s recipes is based on the recommended quantities from the USDA. The USDA’s guidelines on curing salt usage are easily found online.
Curing salt is found in two standardized forms in North America, and it’s important to understand the difference. Throughout this book I’ll refer to two types as either Cure #1 (commonly known as pink salt—it’s usually died pink to prevent accidental ingestion), or Cure #2 (which looks like normal salt, so keep it well labeled). Both types are sold under a variety of different names, usually containing a #1 or #2—such as Insta Cure #1, Insta Cure #2, DQ Curing Salt #1 or #2, and Prague Powder #1 or #2. Although rare, you’ll occasionally see saltpeter in a recipe for cured meat, and while it has a different chemical composition, it still contains nitrates, so you can substitute Cure #2 for saltpeter.
The difference between Cure #1 and Cure #2 is important. Use Cure #1 for any items that will just be cured and not dried, or for items that will dry rapidly (less than 2 weeks). Only use Cure #2 for items that will be dried for longer than 2 weeks.
To understand the effect nitrates and nitrites have on meat, it’s important to first distinguish between them, which may seem obvious, but most people mistakenly treat nitrates and nitrites as interchangeable.
When added to meat, nitrites (NO2) immediately undergo a wide range of complex chemical reactions, which eventually convert the nitrite to nitric oxide (NO), leaving very little nitrite remaining in the meat. Nitrites influence color formation (giving cured meats their pink color), flavor formation (a ham doesn’t taste like roast pork), they reduce the risk of fat rancidity (which is just the oxidation of lipids over time, but is one of the reasons nitrites are so common in industrially produced foods), and, perhaps most important, they inhibit the bacterium that causes botulism, Clostridium botulinum.
In contrast with nitrite, when nitrate (NO3) is added to meat, it doesn’t immediately undergo any relevant chemical reactions; it is important in dry-curing for one key reason: Over time, Staphylococcus bacteria—which will naturally populate whole-muscle dry-curing, or are added through the starter culture in a salami—will populate your drying meat and produce the enzyme nitrate reductase, which slowly reduces nitrate into nitrite. This means nitrate is a reservoir of nitrite—providing a long-term supply of it for items that will be dried and aged for long periods of time, including most of the recipes in this book. The rate of conversion from nitrate to nitrite is variable, and giving an exact time for this conversion is impossible. Nitrate is never used on its own, only in conjunction with nitrite (Cure #2 has both types).
Cure #1 and Cure #2 are not interchangeable, and products like Morton’s Sugar Cure are not a replacement or adequate substitute for either.
The Science of Salting
In salami, salt absorption simply happens when you mix all the salt and seasonings into the ground meat and fat. The surface area of the ground meat is high enough that the salt will quickly and easily be absorbed. No special conditions or even further mentions are needed for successfully salting salami.
In whole muscles, salt absorption and distribution may require several weeks, but the process is simple, reliable, and hands-off. Salt absorption and dispersal will take a couple of days for a thin slice of loin, a couple of weeks for a coppa, but might take 2 months for a large bone-in ham.
The key to salting meat is the process of diffusion. If you remember your high school biology, the concept behind diffusion is the tendency for substances to disperse through a substance until an even concentration, or equilibrium, is reached. For example, if you dissolve salt into a glass of water, you won’t find pockets of saltier water in the glass—the concentration of salt is equal throughout. The same concept can be applied to meat—given enough moisture in the meat for the salt to dissolve, the salt will disperse to create an even concentration throughout the meat. (As a side note to those who remember diffusion and osmosis always being taught together, osmosis is also involved in this process, but osmosis is a type of diffusion, and specifically involves movement across a semi-permeable membrane.)
The process looks like this:
First, salt is applied to the outside of the meat and begins dissolving into the layer of moisture coating the meat. The dissolved salt starts to migrate from the area of high concentration (the salty outside of the meat) to the area of low concentration (the interior).
At the same time, the water inside the meat (a high concentration of water) starts migrating to the salty layer on the outside (a low concentration of water). This results in moisture leaving the meat. Not enough moisture is lost for any significant drying of the meat.
What then follows is a back-and-forth of salt and water. Salt goes in, water goes out, but as the salt concentration increases inside the meat, the water “follows” the salt back in, and everything keeps moving around, slowly reaching equilibrium.
If you’re salting a piece of meat in a plastic bag, and one day you notice lots of liquid in the bag, then return a few days later to find it relatively dry, it’s because the water was reabsorbed by the meat as the interior became more salty.
If you’re salting the meat on a rack, as opposed to in a bag, the exuded liquid cannot be reabsorbed, so you have less moisture remaining in the meat at the end of the process, and the drying process may be a little quicker. You’ll see this in the recipe for dry-cured hams.
As the salt is being absorbed, it’s important to keep the meat cold to limit bacterial growth. Keep the salted meat under 40 degrees F, and if it’s in a sealed bag, you don’t need to worry about humidity, but if it’s open in the low-humidity environment of your fridge, it may start to dry out, which will limit the ability for the salt to move freely—I suggest covering the container that holds the meat with plastic wrap.
It’s impossible for me to tell you exactly how long this process will take, but if you use a precise weight of salt, there is no threat of oversalting, so I’ll usually leave meat for 3 weeks (ham is the exception, and it’s detailed in its own section).
Cure #1 contains standard table salt (NaCl) and sodium nitrite (NaNO2 ), while Cure #2 is salt (NaCl), sodium nitrite (NaNO2 ), and sodium nitrate (NaNO3 ).
Salting and Preservation
To explain why salt is important for the preservation of meat, first understand that bacteria require water to survive and reproduce; stopping bacteria by removing their access to water is the primary preservation technique of dry-curing. Along with a series of other effects, salting meat will reduce the water available to bacteria, but salt does not actually dry the meat.
To clarify, as the salt dissolves and diffuses through the meat, the salt molecules bind with the water molecules, which makes the water unavailable to bacteria, but without actually removing the water from the meat. A raw, unsalted piece of meat is a damp and ideal environment for bacteria, while a raw, salty piece of meat is still a damp place, but has significantly less water available for bacteria, allowing for short-term preservation as the meat is then dried.
The amount of available water in a piece of meat is more accurately described as “water activity,” abbreviated as Aw. Commercial producers closely monitor Aw using digital water activity meters, but observing the weight loss of a drying piece of meat is adequate for the home producer.
It’s important to note that the amount of salt used in dry-curing lowers the water activity enough to provide short-term preservation of the meat, and provides a window of time to dry the meat, but it is not enough salt for long-term preservation. In order to lower Aw enough for long-term preservation, you need to either remove water by drying the meat, or reduce the water activity by heavily salting the meat, like a piece of salt cod or salt-packed anchovies. By employing the drying process in conjunction with salt, you can achieve the long-term preservation of meat without salting beyond palatability.
More from Dry-Curing Pork:
The Facts About Nitrates
To address the health concerns around nitrites and nitrates directly, there are several important facts. First, both will break down to their harmless components if aged properly. For recipes using only nitrites, this may take just a couple of days of curing and resting; for recipes using nitrites and nitrates, the timing is more variable, but occurs as the meat hangs and dries. To speed this process, commercial bacon producers use a curing accelerator, usually ascorbic acid, or sodium erythorbate, which increases the speed of the various curing reactions and the breakdown of nitrite. The use of a curing accelerator assures that very few residual nitrites are left in the meat; if you are concerned about nitrites remaining in your bacon, pancetta, or guanciale (all products that are usually cooked), use a curing accelerator to speed their breakdown. Nitrates are only a concern as they will eventually break down into nitrites.
With this background knowledge, the specific health concern surrounding nitrites is that potentially carcinogenic compounds are created when cured meat, containing residual nitrites, is burned. These compounds, called nitrosamines, are only a concern for those people who like their bacon burnt. If there are no remaining nitrites, and you do not burn your bacon, these compounds will not form.
Finally, if your concern is that nitrites and nitrates are unnatural preservatives, be aware that they are found in high levels in most leafy green vegetables (spinach contains large quantities) throughout the natural world, as well as in heart medications, desensitizing toothpaste, and — most important for our world’s population — fertilizer. The nitrites and nitrates found in curing salts are created through an industrial process (the same process as fixing nitrogen for fertilizer). If you prefer to use a natural source of nitrites and nitrates, vegetable powder substitutes are available from most sausage supply companies (be aware that the nitrites and nitrates in these powders most likely originated from a industrially made fertilizer — they’ve simply been passed through a plant before arriving in your kitchen).
If you choose to avoid nitrites, please take the time to research their importance in more detail before removing them from any recipe. Under no circumstances can salami be safely made without nitrites. Any labeling of commercial salamis that says “uncured” or “made without additional nitrites or nitrates” is misleading. Those salamis do contain nitrites; they’re just added through vegetable powder, instead of in a pure form (this goes for “uncured” hot dogs and bacon as well). The misleading packaging is a result of a flaw in the USDA’s extensive regulation of cured meats. Some producers use “uncured” as a marketing tool, but others would prefer not to mislead consumers — yet their hands are tied by labeling restrictions.
This excerpt has been reprinted with permission from Dry-Curing Pork, by Hector Kent, and published by The Countryman Press, 2014.