Salt serves several functions in food (six, to be exact)—as a preservative, to add texture, enhance flavor, as a binder, and color enhancer. This is why nearly every recipe includes salt on its ingredient list.
When cooking, we mainly include salt to enhance the flavor of the food. Salt brightens the foods' flavors and facilitates a balance between sweetness and acidity. But since it is somewhat easy to oversalt and therefore ruin a dish, home cooks tend to under-season, which results in a bland meal. In turn, those who are eating often use a heavy hand with the salt shaker, which doesn't improve the dish and only makes the dish taste salty.
When watching professional chefs cook, you will notice they salt (referred to as "season") the food at several stages and not just at the end before serving. This is because the chemical makeup of salt enhances the flavor of food as it cooks, brightening the dish. And sprinkling with a finishing salt at the end will add texture as well as another layer of taste.
The Science of Salt
Salt, or sodium chloride, changes its composition when it comes into contact with water. It breaks down into two parts—positive ion and negative ion—allowing it to deeply penetrate the food and simultaneously draw water out of the food (which is why salt is a component of brining). This two-pronged process enhances the food's flavor while preventing spoilage. The salt penetrates the food more slowly when cold but still moves at somewhat of a slow pace when heat is added, creating a more even flavor, which is why it is best to add salt toward the earlier stages of cooking versus just at the end.
The sodium portion of salt masks any bitterness by decreasing the sourness of acid and increasing the sweetness of sugar. By quashing the unpleasant flavors, the favorable tastes are able to come to the forefront, making the food taste good.
When to Salt
Most recipes will call for adding salt along with other seasonings, such as black pepper, at certain points during the cooking process. The instructions may be to include with certain ingredients and then later to "season to taste," or "check seasoning and add salt if needed." It is important to follow this guidance as salt will affect food differently at different stages of cooking. Since salt takes a while to penetrate the food, pulling out its natural flavors, it needs time to do so, hence why adding salt toward the beginning of the cooking process is ideal. Simply adding at the end doesn't provide enough time for the salt to do anything but just add a salty taste.
For example, when you salt raw vegetables before they go in the oven to roast, the salt has time to penetrate the food while it cooks, masking its bitterness and bringing out the natural sweetness. Then a sprinkling of salt at the end adds that bit of saltiness that we all crave, complementing the sweet and nutty flavors of the vegetables.
Salting Vegetables and Meat
The technique for salting vegetables and meats may differ depending on the recipe you are making. Some may direct you to salt vegetables before adding to other ingredients to remove the liquid from them, as in a coleslaw or cucumber salad. Meat can be a little more complicated as there is a window of time when it is not recommended to salt. Salting meats first brings the juices to the surface, so if you cooked the steak, for example, while there is this salted juice on the outside, the meat would steam, not form a nice outer crust, and be dry inside. However, if you wait several hours, this salting liquid will be reabsorbed, adding flavor and tenderness to the meat. So, you either need to salt meat way ahead of time or salt right before cooking.
The Different Salts
You will find that some recipes call for a specific type or grind of salt beyond ordinary table salt. In some cases, it will not matter if you use table salt, but in others, it can make or break the dish. Your best bet is to follow the recommendation of the recipe to achieve the desired result. For example, most baking recipes will call for table salt because it dissolves easily, strengthens gluten, and controls yeast growth. However, it has been stripped of its natural flavor during the refinement process, so it isn't ideal to use when seasoning food.
The best salts to add during the cooking process are kosher salt and sea salt. Just keep in mind that these salts are more irregularly shaped than table salt, so the same measurement will result in less kosher and sea salt than table salt and you will need to adjust accordingly. A good rule of thumb is 1 tablespoon of kosher salt equals 2 teaspoons table salt.
Finishing salt used to be something only chefs would sprinkle on top of a dish, but now that we have more access to "gourmet" ingredients, the home cook can enjoy implementing this flavoring technique. A favorite of chefs is fleur de sel as it is pure in flavor and enhances sweetness, which is why it is used often in desserts.
How Much Salt
If a recipe simply states, "salt to taste," you may be wondering what a good amount to begin with is. Use this general guide to help you measure correctly and bring out the food's natural flavors to their fullest.
1 teaspoon per quart for soups and sauces
2 teaspoons per pound for boneless raw meat
1 teaspoon per 4 cups flour for dough
1 teaspoon per 2 cups liquid for cooked cereal
1 teaspoon per 3 cups water for boiled vegetables
1 tablespoon per 2 quarts water for pasta
If you have oversalted a dish, unfortunately, there really isn't much you can do besides make more of the recipe without salt and add to the first batch. Adding potatoes will remove some of the salt, but not enough to really make a difference.