The Science Of Salt
"Let there be work, bread, water, and salt for all." Nelson Mandela
Salt is the single most important flavor enhancer of them all. Period. This tiny water soluble rock reduces the taste of bitterness, balances sweetness, physically expands taste buds, and just a small amount can really wake up a dish. It can also aid in moisture retention during cooking and even tenderize meat (see my article on brining). As we know, there are also health issues associated with its overuse.
Salt is a natual mineral, NaCl, a crystal made of one ion of sodium (Na) and one ion of chloride (Cl). There are many kinds of commercial salt, but all salt is sea salt. That's right, all salt originally came from sea water which is about 4% saline containing about 1/4 pound per gallon.
Salt is so vital to society and health that the words salt, saline, and salary have the same root, the Latin word salarium which was the money paid to a Roman soldier to buy salt.
Salt is not evil
I know that a lot of health experts are taking potshots at salt because it makes food taste better and can entice us to eat too much. I know that many of us have been told to limit salt intake because it can raise our blood pressure, but before you swear off the stuff and start posting the "you idiot" comments below, know this:
Salt is vital to all living things. It is called an "essential nutrient" for humans, which means that our bodies do not make it, so all our salt must be ingested. From the Mayo clinic: "Your body needs some sodium to function properly because it: Helps maintain the right balance of fluids in your body; Helps transmit nerve impulses; Influences the contraction and relaxation of muscles."
When dissolved in water, salt conducts electricity and it is essential for aiding the transmission of signals along your nervous system and in your brain. On average we all have about seven tablespoons of salt in our systems. That's why all your bodily fluids are salty: Blood, sweat, and tears.
Salt is also a preservative and antimicrobial, which is why so many meats and vegetables were brined, pickled, or packed in salt before refrigeration. Think prosciutto and corned beef. Salt raises the temperature at which water boils and lowers the temp at which it freezes, and it is also a heckuva stain remover.
On the flip side, too much salt in your diet can increase your blood pressure, a condition that has been implicated in cardiovascular disease. Because of this, there are a lot of people worried that we consume too much salt, especially because prepared foods like frozen dinners and fast food from restaurants have a lot added. But the correct amount of salt consumption is still not known, varies from person to person, and its impact on our health is still being explored. In 2013 an expert committee, organized by the Institute of Medicine at the request of the Centers for Disease Control and Prevention, studied the research, especially recent research, and reported that there is no reason to aim for sodium levels below 2,300 milligrams a day (about 1/10 an ounce) as some doctors recommend. In fact, the group said low sodium diets may be as risky as high sodium diets, although it would be hard to avoid enough salt to endanger yourself. Click here to read an analysis of the report in the New York Times, and click here to read the original report. In addition, my article on undertanding what you read about diet and health might be helpful.
If you remain worried about too much salt in your diet, the secret is to control it yourself. The secret is to cook! Buy unprocessed foods and season them yourself. If you avoided fast foods and processed foods, you will never have to worry about too much salt in your diet.
The different kinds of salt
There are many types of salt, but when they are used in cooking it is almost impossible to taste the differences. But there is an important reason to pay attention: All salts are the same when you measure by weight, but most recipes measure salt by volume (teaspoons, tablespoons, cups, etc.) and this can cause a problem if you are not careful.
Table salt is sea salt that has usually been mined from salt domes found underground. It is dissolved in water, refined and "purified" and ground into small uniform cube shaped grains. Anti-caking agents have been added so it works well in salt shakers. Some also also have iodine as an additive to help prevent iodine deficiency, a leading cause of mental retardation, thyroid problems, decreased fertility rate, and increased infant mortality. Not all table salt has iodine.
Kosher salt has larger flake shaped grains and also has small amounts of anti-caking additive but no iodine. Many chefs prefer kosher salt because the larger grains make it easier to pinch. There are two popular producers of Kosher salt, Morton's, and Diamond Crystal. Their grain size is different, so I have standardized on Morton's in all my recipes.
Pickling salt (a.k.a. canning salt) dissolves well in cold water so it is a good choice for brines. It lacks iodine and anti-caking additives, so it is the best choice for pickling.
Sea salt. The aura surrounding sea salt is a bit of a scam. All salt comes from the sea, so all salt is sea salt. But in the marketplace nowadays, the term is usually used to describe salt that has been made by humans creating shallow ponds and allowing the water to evaporate. It does not just happen naturally. Usually the grains are large.
If you've noticed the rainbow colors on the water on the south shores of San Francisco Bay as you fly into SFO, you're looking at salt drying ponds. Sun dried sea salt usually has minute amounts of minerals from the sea that can give it subtle flavors and colors ranging from pink to black. According to Castro and Huber's, Marine Biology textbook sea salt usually contains sulphate, magnesium, calcium, potassium, bicarbonate, bromide, borate, strontium, and fluoride, in descending order. It can also contain other impurities including metals, pollution, fish poop, microbial spores, and even radioactive elements such as radium, uranium, and polonium. Whatever is in the sea. But what the heck, it's "natural". The kicker is that some "sea salt" is refined in a similar fashion to table salt.
Grain size can vary significantly from producer to producer, but large grains can provide pops of flavor when used at the table. But beware, large grains don't dissolve easily and can feel gritty, even rocky, between your teeth. But in the same bag of large grains there can be fine powder. That is why I don't use it in cooking. It is impossible to regulate quantities. I use it only as garnish at tableside. Sea salt can also be very expensive.
Seasoned salts. Grocery stores sell seasoned salts like garlic salt (approximately 3 parts salt to 1 part garlic powder) and celery salt. I never use them in cooking since I prefer to control the amount of all ingredients. That said, I make a seasoned salt with herbs and large grain salt and I place them on my dining table as a finishing salt. It is super on potatoes, pastas, veggies and other dishes. Click here for my recipe for Seasoned Salt.
Pickle salts. Another fun technique to make unique salts is to take pickle juices, dry them in a dehydrator or by just leaving them in a non-reactive pan to evaporate. Then scrape them up. You can use them like this, or grind them in a mortar and pestle, coffee grinder, or blender. Try making them from the juices left after you empty a jar of dill pickles, sauerkraut, pickled mushrooms, pickled peppers, onions, whatever you can find!
Curing salts should never be used to season food in the cooking process or at the table. Curing salts were created centuries ago, before refrigeration, as a method of preserving meats such as bacon, hams, and corned beef. They all contain salt and nitrite, and some contain both nitrite and nitrate. Both these preservatives are very effective against the deadly botulism bug, a common problem with improperly cured meats. Most curing salts are colored pink with a small amount of red dye so you don't confuse them with table salt. The small quantities used in curing meats is harmless, but in large quantities can be lethal. Pink salts are not the same as pink Himalayan rock salt which is pure salt with trace elements that give it the pink color! Pink salts must be stored where children cannot get tat them.
You can skip the curing salts and just replace them with table salt, but I strongly recommend that you do not. The meat will taste pretty much the same, but it will be tan in color and you will need to smoke it at more than 200°F and keep it refrigerated or frozen. A lot of people fear nitrites and nitrates based on research that has been contested. Click here for more info on nitrites and nitrates.
Some important words of caution. Curing meat is not like any other recipe. It is not like brining a turkey or chicken for a few hours. Please read my article on the science of curing meats.
Prague powder #1 or Insta Cure #1 or Pink curing salt #1 or Sure Cure. This is the standard for quick curing meats. It is approximately 94% plain old sodium chloride with approximately 6% sodium nitrite with some anticaking agents and a touch of red dye that makes it pink so you won't mistake it for table salt or sugar. It's not easy to find this stuff in groceries, but butcher shops, sporting goods stores where they sell sausage making gear, and this link to Amazon.com carry it.
Prague powder #2 or Pink curing salt #2. This has approximately 6% sodium nitirite, 4% sodium nitrate, and the remaining 90% is plain old sodium chloride with some anticaking agents and red dye. The exact precentages may vary from manufacturer to manufacturer. It is usually used in sausages and other meats that will be kept for weeks or months. The nitrate breaks down into nitrite with time so it remains active over months.Like a time-release capsule. It is used to extend shelf life. It is mostly used for long warmer cures, like the dry cures used to make prosciutto and country hams.
Insta Cure #2 has only about 1% nitrate.
Saltpeter. Another name for potassium nitrate, saltpeter was once used extensively in curing meats. It has been replaced by curing salts. It cannot be used as a substitute for curing salts in any of my recipes.
Morton Tender Quick contains 0.5% sodium nitrate and 0.5% sodium nitrite, and anticaking agents. Despite the misleading name, it is a curing salt and is not a tenderizer.
Readycure is common in Canada and it is only 1% nitrite, so it is not a good substitute for curing salts that are typically 6% nitrite.
Measuring different salts
You must be aware of which salt you are using when you follow a recipe that measures by volume because the grain size can make huge difference on the amount of sodium, i.e. saltiness. For example, one teaspoon of table salt, which is a small cubic shaped grain, contains less air than one teaspoon kosher salt, which is a larger flake and has more air between the grains. So if the recipe calls for a teaspoon of Morton's kosher salt and you use a teaspoon of table salt, the results will be much saltier. If the recipe calls for salt by weight, like eight ounces, it doesn't matter which salt you use, the volume may be different, but the amount of sodium will be the same!
Here's an approximate conversion table for when you are measuring by volume.
1 volume unit of most table salts = 1 volume units of Morton's Pickling Salt
1 volume unit of most table salts = 1.25 volume units of Morton's Kosher Salt
1 volume unit of most table salts = 1.25 volume units of Windsor Kosher Salt
1 volume unit of most table salts = 2.1 volume units of Malden Sea Salt
1 volume unit of most table salts = 2.25 volume units of Diamond Crystal Kosher Salt
Other useful conversions
1 cup table salt = 8 ounces by weight
Salt = 2.16 times the density of water
This means that if your recipe calls for 1 teaspoon of table salt, but you want to substitute Morton's Kosher Salt, use just a bit less than 2 teaspoons. If your recipe calls for 1 teaspoon of Morton's Kosher Salt and you want to substitute table salt, use just a tiny bit more than half of a teaspoon. If a recipe calls for Morton's Kosher Salt and you use Diamond, use about half the amount.
For this reason, it is far better to measure salt (as well as sugar and flour) by weight rather than volume. If I knew that every kitchen had a good digital scale I would switch to salt by weight in my recipes in an instant. I use the OXO Good Grips Stainless Food Scale with Pull-Out Display.
Dry brine. Sprinkle the meat with about 1/2 teaspoon of kosher salt per trimmed pound, wrap in plastic wrap to keep other foods from contacting meat juices, and refrigerate for 2 to 12 hours depending on thickness.
Basic wet brine. Add one cup of hot water to a two cup measuring cup. Then pour in salt, any salt, until the water line reaches 1.5 cups. Add this to 1 gallon of cold water. Produces a 6.3% brine.
1/2" thick meat should be brined for about 1/2 hour in the refrigerator
1" thick meat should be brined for about 1 hour in the refrigerator
2" thick meat should be brined for about 4 hours in the refrigerator
3" thick meat should be brined for about 12 hours in the refrigerator
Briners beware of double salt jeopardy!
Rubs are a great way to add flavor to meat. Brines are also a great way to add flavor as well as moisture. Rubs often contain a lot of salt. You can use both a rub and a brine, but beware of double salt jeopardy. If you use a brine and then a rub, you should make your own rub mix and leave the salt out of the blend. A salty rub on top of brined meat can make the meat unbearably salty. Never brine meat that is labeled "enhanced" or "flavor enhanced" or "self-basting" or "basted" because they have been injected with a salt solution. Remember, you can always add salt, but there's no taking it away.
Adding salt to pasta and potatoes
It is common to add salt when cooking pasta or potatoes and many other foods. If you add the salt while the water is cold it can sink to the bottom and cause pitting. All-Clad and other manufacturers recommend adding the salt after the water is boiling.