Salty Tales

Salt is probably the oldest of all seasonings. Besides imparting its own salty taste it subtly enhances the flavour of other foods. We salt soups, sauces, salads, meats, poultry, fish, charcuteries, vegetables, pasta, bread and even desserts. But is it always for the right reason? Let’s take a quick look a several myths surrounding the use of salt in cooking.

True or false?

1. Salt raises the boiling point of cooking for pasta

TRUE.Salted water has a higher boiling point than unsalted water. However, when it comes to cooking pasta, the effect of the temperature increase is negligible. Recommendations for how much salt to add vary from continent to continent. In North America, pasta manufacturers usually suggest using 15 ml (1 tablespoon) salt in 5 litres (20 cups) water for 500 g (1 lb) dried pasta. European manufacturers are more generous and recommend following the “10–100–1,000” rule: 10 g salt (about 10 ml or 2 teaspoons) for 100 g (3.5 oz) pasta in 1,000 ml (4 cups) of water. But even that higher concentration will raise the boiling point of water by barely 0.2°C (0.36°F), a tiny difference that will have no appreciable effect on the time it takes to bring the water to a boil or to cook the pasta. Why salt the cooking water, then? Simply to make the pasta taste better. Also, salt limits gelatinization (the swelling of starch) on the pasta’s surface, which helps keep the noodles from sticking together. Should you salt the water before or after it comes to a boil? While it doesn’t matter from a cooking standpoint, you’re best off adding the salt after the water is boiling. Add salt to cold water and it will sit on the bottom of the pot, where it can corrode the metal and cause pitting. If you do add the salt beforehand, be sure to stir the water until it dissolves.

2. Never salt a steak before cooking

FALSE. This myth claims that salting an uncooked steak causes it to release some of its juices, on the one hand drying out the meat and, on the other hand, making the surface wet and thus harder to brown. What’s important to understand here is that salt acts only on the surface. The amount of water drawn out by the salt is minimal and has no noticeable effect on the steak’s juiciness or ability to brown. So, feel free to salt before cooking, after cooking or both before and after cooking!

3. Adding salt to cooking water helps green vegetables stay green

TRUE. But before dumping tons of salt into the cooking water, read on. Green vegetables owe their colour to the chlorophyll in their cells. At
the centre of each chlorophyll molecule (which is structurally similar to haemoglobin) is a magnesium atom. Green vegetables change
colour during cooking when the magnesium atom is displaced by hydrogen ions derived from acidic compounds that are also present in the vegetable’s cells. These acidic compounds are released as the cells soften during cooking. This slight chemical change shifts the chlorophyll’s colour from green to yellow-brown. Studies have shown that adding salt to the cooking water for vegetables like green beans and spinach protects the chlorophyll, probably by preventing the magnesium atoms from being displaced, but the effect is quite subtle. A more effective way to prevent green vegetables from becoming dull is to keep cooking times short, preferably under 5 to 7 minutes.

4. Soups and sauces can be made less salty by adding potato slices to them

FALSE. It’s true that potato slices will absorb a little of the cooking liquid and any salt it contains. But potatoes aren’t selective; they don’t absorb only salt. So how can you fix an oversalted soup or sauce? Dilute it! Remove some of the sauce or broth and replace it with more of the soup or sauce’s main ingredient (milk, broth, wine, tomato juice, etc.). If the resulting product is too thin, thicken it with a little cornstarch or flour.

5. Salted water takes longer to boil unsalted water

TRUE. But with the salt concentrations normally used in cooking, the difference will be a few seconds at most. To increase the boiling point of water by a mere 1°C (1.8°F), you’d need to add 58 g of salt (about 50 ml or 1/4 cup) for every litre (4 cups) of water. But why does boiling water start to bubble violently when you add salt? Because before the salt crystals dissolve, they provide a place for bubbles to form. The same thing would happen if you added sugar or even fine sand.

6. Salt stabilizes beaten egg whites

FALSE. Contrary to what you sometimes hear, salt does not prevent beaten egg whites from deflating. In fact, it may even decrease their stability. Egg whites can be beaten into a stiff foam because beating causes their normally folded proteins to unfold, bond and form a mesh around air bubbles created by the beaters. These bonds are essential to the foam’s stability. When salt dissolves in egg whites, it dissociates into its two constituent parts, positively charged sodium ions and negatively charged chloride ions. These ions are attracted to the electrically charged bonding sites on the proteins, which prevents them from forming a solid meshwork. If you need to add salt to egg whites for taste, it’s better to do so after they’ve been beaten. To stabilize egg whites you’re going to beat, use cream of tartar instead.

7. Salt prevents dried legumes from softening during cooking

FALSE. In fact, dried legumes (beans and peas) will cook faster if salt is added to the soaking water. How? By acting on the pectin, the plant equivalent of concrete, which cements the cells together. Within the pectin are magnesium “bridges” that strengthen the pectin’s structure. When dried legumes are soaked in salted water—about 10 ml (2 teaspoons) salt per 1 litre (4 cups) water is sufficient—the salt’s sodium ions displace the magnesium bridges weakening the pectin’s structure. This makes the pectin more susceptible to degradation during cooking, so the legumes cook faster. Adding a little salt to the cooking water is optional and doesn’t interfere with softening.

8. Salting eggplant makes it less bitter

TRUE. But not the way you think it does! Salt is often sprinkled on eggplants to draw out moisture and reduce their bitterness. The
theory is that the water carries away some of the eggplant’s alkaloids, the molecules that give the vegetable its bitter taste. Yet while it’s true that salted eggplants shed water, most of the alkaloids remain in the plant cells. So why does salted eggplant taste less bitter? Research has shown that salt—or rather the sodium it contains—can reduce our perception of the bitter taste of foods and drinks (see sidebar). If salted eggplant tastes less bitter, it’s because the salt is playing tricks on your taste buds!

9. Salt is not an essential ingredient in desserts and pastries

TRUE. Salt doesn’t play a significant functional role in desserts and pastries. When prepared without the usual pinch of salt, cakes will rise, pie dough will be as flaky, custards as silky. But what about their taste? Salt improves the flavour of food: it reduces bitterness, enhances aromas and adds what food scientists call “roundness” to foods, including sweet ones. A dash of salt—only a little is needed—brings out the flavour of vanilla, chocolate, butter or any other flavouring. That may explain why salt caramels are all the rage these days.

Tasting is believing

Try this experiment, which shows how salt alters the taste of food. Place some grapefruit sections on two plates. Lightly dust one of the plates with salt (it doesn’t take much), then compare the taste of the salted and unsalted grapefruit. The salted grapefruit will taste less acidic, less bitter and surprisingly sweeter, but not salty. What’s going on? The salt isn’t reacting chemically with the food by neutralizing the grapefruit’s acidity or bitterness. Instead it modifies how your taste buds interact with other taste molecules.

Christina Blais

For Christina Blais, explaining food chemistry to the masses is as simple as making a good omelet. Holding a Bachelor and Master degree in Nutrition, she has been a part-time lecturer for over 30 years in the Department of Nutrition at the Université de Montréal, where she teaches food science courses. She has been sharing the fruits of her experience with Ricardo since 2001, during his daily show broadcast on ICI Radio-Canada Télé. And diehards can also read her Food Chemistry on our website. You can follow her on Facebook at @Encuisineavecchristinablais.