The Science of Salt

Nov 1, 2019 | Science | 0 comments

Table Salt Salt Shaker Salt Cooking Salt Glass

The kitchen’s most popular seasoning and how it works.

Salt, the only rock we eat, is more than just a seasoning—it’s an essential flavor in our food. It can intensify aromas, balance other flavors, make meat taste juicier, and preserve food for months or even years. Yet a heavy hand with salt can easily ruin a dish. Here’s how to cook wisely with the world’s most vital mineral.
How does salt affect the flavor of food?
In a number of ways. Salt is one of the five basic tastes that we’re hard-wired to detect (along with bitter, sweet, sour, and umami or savory). It enhances foods by essentially turning up the volume of their salty flavors. Salt can also dial down the taste of bitter foods by suppressing our perception of bitterness, and balance other tastes like sweet and sour (salt added to desserts or vinaigrettes, for example). Salt also unravels (or denatures) the tight spiral structure of proteins, making their flavors tastier and more aromatic.

Even the texture of salt enhances the taste of food. Flake salts like Maldon or Halen Môn Gold sprinkled over a green salad transmit crunchy bursts of saltiness that enhance the soft texture and mild flavors of lettuce leaves and other vegetables. And surprisingly, salt brings out aromas, too, because it helps release aroma molecules from food into the air. These stimulate our olfactory receptors, helping us to smell things.

How does salt preserve food?
Picture what happens when you sprinkle salt on a sliced cucumber; within a few minutes, the salt is dissolved in a pool of cucumber juice. That’s because water flows through food cell walls towards greater concentrations of dissolved particles, proteins, and pigments. When you rub salt on a vegetable or meat, it dissolves in the food’s exterior moisture, creating a concentrated solution that draws more water from the interior to the surface.

This process illustrates salt’s role in preserving meat for jerky, ham, or hard-cured salami. The salted meat is placed in circulating air, which evaporates emerging water so the meat dries out. Because microorganisms need moisture to survive, drying meat makes it inhospitable to molds and bacteria, thereby lengthening the storage life of some sausages and hams for months.

How does brining—soaking meat in a salt solution—make it juicier?
In brining, the moisture flow described above is reversed. The concentration of salt in the brine is more dilute than the protein-rich liquid inside the meat cells, and so the brine moves into the flesh. There, the water from the brine bonds to the proteins, resulting in juicier meats. As salt enters the meat cells, it alters the structure of the muscle fibers and proteins, swelling their water-holding capacity by about 10 percent. Since most meat loses about 20 percent of its moisture during cooking, brining meat can cut moisture losses by almost half.

How and when should I salt my food?
Not only does salt add flavor, but it can also alter the structure of proteins, speed the cooking of vegetables, and make sauces thicken more quickly. Therefore, the answer to this question depends on what you’re cooking.

Before cooking
Raw vegetables Salting crisp, juicy vegetables, like cucumbers or cabbage, before tossing in a salad rids them of moisture that would otherwise water down the dressing. (Myth buster: It’s said that salting eggplant reduces its bitterness by releasing bitter alkaloids with the drained water. This isn’t the case. The reduction in bitterness is due to salt’s ability to reduce our perception of bitterness on the palate.)

Grilled meats Seasoning meats with salt or a salty spice rub draws out protein-rich juice that dries on the surface during cooking, creating a crisp, deeply seasoned crust.

Dried beans When soaking dried beans before cooking, adding 2 tsp. salt per quart of water greatly reduces cooking time by replacing magnesium in the cell walls with sodium, making the cells dissolve more easily when heated. (Another myth buster: It’s said that salting beans before cooking slows down the cooking, but it’s actually adding acid or sugar that slows it down, not salt.)

During cooking
Cooked vegetables Salting the water for boiling or blanching vegetables speeds up cooking by hastening the breakdown of hemicelluloses, substances that help hold vegetable fibers together. Because pure water draws salts and other soluble nutrients from the interior of vegetables, salting vegetable cooking water also minimizes nutrient loss.

Pasta, rice, and potatoes Salting the water for boiling these starchy ingredients improves their flavor by allowing the salt to permeate the ingredients more deeply. Also, when dried pasta hits boiling water, starches on the surface of the noodles gelatinize and become sticky. Salt limits this starch gelation, so liberally salting pasta water reduces stickiness as it flavors the pasta.

Starch-thickened sauces Thickening a sauce with flour or cornstarch reduces its flavor. This is because the long-chain carbohydrates present in starches and flours bond sodium ions to themselves, thereby reducing our perception of sodium and aromas in the sauce. The remedy is to add a little more salt.

After cooking
When salting for seasoning only If you’re adding salt solely for seasoning and not for any of the reasons mentioned above, the best time to do it is at the end of cooking. That way, the salt crystals hit your palate directly, and you get the greatest flavor impact with the least amount of salt. Also, by salting at the end of cooking, it’s easier to salt to taste and avoid oversalting.

When using unrefined, unground salts Salts like fleur de sel, sel gris (gray salt), and flake salts like Maldon contain crystals of various sizes, so they dissolve on food and across your palate over time. Adding them after cooking results in prolonged and fuller flavor impact.

A Cook’s Guide to Salt
There are two main types of salt. Rock salt is mined from the earth by digging or by pumping water into salt deposits to dissolve the salt, and then evaporating the resulting brine in vacuum chambers to recrystallize it. Sea salt is harvested from ocean water that’s evaporated in open-air pans, in vacuum chambers, or by fire. Within these main categories are several subcategories of culinary salts. Here are the most common types:

Unrefined salt Usually sea salt (but sometimes rock salt), evaporated in open-air pans and left unwashed so it retains trace minerals and other components that provide unique flavors, aromas, colors, and crystal structure. this category includes fleur de sel, gray salt, flake salt, and some flavored salts. often used as a finishing salt at the end of cooking.

Table salt Tiny, uniform, granulated crystals of refined salt containing 95 to 99 percent sodium chloride and usually 2 percent anticlumping agents like sodium silicoaluminate (an aluminum and silicone compound). often used in baking recipes.

Iodized salt Table salt supplemented with potassium iodide or iodate to prevent iodine-deficiency conditions like mental impairment and goiter. in areas where fish and sea vegetables (primary sources of iodine) are scarce, iodized salt remains the most effective method of preventing iodine-deficiency diseases. often used like table salt.

Kosher salt Coarsely ground refined salt (sometimes including an anticlumping agent) manufactured for kosher butchering, where its large crystals draw blood and moisture from the surface of meat. often used for cooking because it’s easy to pinch and sprinkle. curing salt refined salt containing added nitrite or nitrate; used to cure meats.

Pickling salt Additives like anticaking agents and iodine can contribute off flavors to pickles, so some salt manufacturers sell additive-free salt as pickling salt.

Pretzel salt A coarse refined salt with dry, solid grains that limit the absorption of fat from the pretzel, which can make exposed crystals blacken during baking.