Taste: Surprising Stories and Science About Why Food Tastes Good (34 page)

Goldstein went to bed early, tossed fitfully, got up, vomited most of the water she had drunk, and went back to bed. When her teammates noticed her moaning early in the morning and could not wake her, they called an ambulance. Two days later Goldstein awoke in a Rapid City hospital to find that her parents had flown in from Florida and her friends were clustered around her. She had thrown her body into a metabolic condition known as
hyponatremia
. Her body fluids had too much water and not enough sodium, which had affected her blood pressure and brain. For days afterward, her parents were terrified that she had sustained brain damage. She could have died had she not been treated. Luckily, she did not die.

Since then, Goldstein has become a nurse practitioner, and today she is healthy and much less obsessive about her eating and exercising.

Goldstein’s experience shows both how natural and how important eating salt is. For some reason, though, she didn’t know she was close to death and didn’t crave salt the way someone dying of dehydration craves water. To quote Micah Leshem of University of Haifa, an expert on salt intake, “We will seek salt to please our palate, but not to save our life.”

Salt serves an important role in the glorious transformation of foods by cooking. When you cook certain foods, they brown on the outside, which can change and intensify their flavors. Browning also creates new flavor compounds that humans generally find desirable. Uncooked bread dough, for instance, is pale white and doesn’t taste very good if you have the guts to eat it. The aroma and golden crust of a perfectly baked sourdough baguette, on the other hand are crave-able. A raw steak doesn’t hold much appeal (unless you doctor it up with the makings of tartare or carpaccio, both of which rely on the addition of other ingredients). But the browned, crisp edges of an expertly grilled steak can make your mouth water.

These types of browning are due to the Maillard reaction. Salt helps release the volatiles that occur during the Maillard transformation that makes food more appealing, such as the aromas of bread baking and steak grilling. Says Paul Breslin, “The smell of fresh-baked cookies, the smell of fresh-baked bread, is not the same in the absence of salt.”

I can attest to this. On a trip to the Italian countryside in Tuscany, I ate some of the best food of my life. It was my first trip to Italy and I relished every bite. I had a tiny scoop of gelato every evening. I reveled in multiple plates of pappardelle with rabbit ragù and cemented my love affair with the Italian bubbly wine prosecco. Everything seemed to taste better than I expected, as if the Tuscan air had deposited a layer of deliciousness atop already amazing food. That is, everything except the bread.

Tuscan bread is made without salt. It is pale and bland and lacking in characteristic bready flavor. Theories abound as to why this region of Italy, alone, bakes bread without salt. One story is that ancient tariffs on salt upset the Tuscans so much they staged a tea party–like backlash: they simply stopped using it in their bread. I’m skeptical about this theory because the pastas and cured meats of Tuscany are wonderfully full-flavored and full-salted, although these give rise to another theory. This one holds that the salty meats and cheeses of Tuscany demanded saltless bread as a foil. I’m not buying this, either. Spain and France have long histories of curing meat and making cheese and their bread contains salt, which enhances the pairing. The rest of Italy eats salty meats, cheeses, and, yes, salty bread. Why in the world would this part of Italy hold on to this taste-killing tradition, regardless of its origin? Paul Breslin backs me up: “Bread with salt in it has more browning reactions occurring and it will smell more like the
classical sort of fresh-baked bread aroma, which many find more desirable.” Except, apparently, the Tuscans.

My grandfather used to salt his grapefruit half, which my grandmother served with a maraschino cherry in the middle. I always wondered: why the salt? He said that the salt made the citrus fruit taste sweeter. As a child, I thought, How could salt—which tastes salty—make grapefruit taste sweeter? It’s the same grapefruit half before and after salting, and he was adding salt, not sugar. But when I tasted it, I found he was right.

My grandfather knew something from experience that has only recently been explained by science, an effect called mutual suppression. The right amount of salt makes grapefruit taste sweeter. The right amount being a threshold level, which doesn’t make the grapefruit taste salty because it’s just below your threshold of detection.

In fact, lemonade is another example of mutual suppression, a sort of canceling-out phenomenon whereby the Basic Tastes sour and sweet suppress each other. Imagine three batches of liquid: the first is two quarts of pure unsweetened lemon juice; the second is two quarts of sugar water; the third is lemonade made from two quarts of lemon juice plus two quarts of sugar water. If you tasted each, you would say that the pure lemon juice was very sour and the sugar water was very sweet. You would find the lemonade less sweet than the sugar water and less sour than the lemon juice.

When you add salt, though, something curious happens. Salt acts as something of a taste superhero, thwarting the bad guys while assisting the good guys. When you add salt to food, it suppresses “bad” tastes, such as bitter or sour. But salt isn’t as punitive to the “good” tastes of sweet and savory. Salt releases the desirable flavors from suppression by the bitter or sour tastes like Superman freeing Lois Lane from Lex Luthor. The result of this salt superheroism is that a pinch of salt can make bad things taste less bad and good things taste better. If you perform the Experiencing Mutual Suppression exercise at the end of this chapter you’ll taste this phenomenon firsthand. Sweetened bitter tea tastes less bitter and more sweet when you add a touch of salt. My grandfather
was
making his grapefruit taste sweeter with salt by suppressing the sour and bitter tastes while the sweetness actually
stayed the same. After adding salt he could taste the sweetness more clearly because it was released.

We often use this knowledge of taste suppression at Mattson. We may add a tiny dash of salt to a formula where you would not expect it, such as hot chocolate or dessert sauce. Chefs also use this technique, many without knowledge of the underlying science. They just know that the end result is that a recipe tastes better with a tiny bit of salt added to it.

The chapter on smell explains that the aroma of a food comes from its volatile compounds. In other words, as a soup simmers on the stove or a pie bakes in the oven, the volatile ingredients in the soup and pie start to waft off. The compounds in the garlic, onion, and celery or the apples, butter, and cinnamon move from the cells of the food and into the air. That’s when you start to smell the wonderful aroma of Grandma’s matzoh ball soup or Auntie’s apple pie. Adding salt to food makes it release more aroma—the salt nudges aromatic compounds out of the cells of the food so that they volatize and you can smell them. Salting raw tomatoes makes them
smell
more tomatoey. And since smell makes up much of flavor, salt increases the signature flavors of a food.

We perceive salt through a receptor channel in the taste bud, whereas we perceive sugar and bitter through a hand-in-glove type of receptor connection that is easier to fake. Hence the proliferation of sugar substitutes on the market, while the quest for the holy grail of the food industry continues: a salt substitute that tastes like salt.

Salt is often used in processed foods to assist in the “functionality” of the food—salt makes meat seem juicier when it’s frozen and recooked at home in your skillet, on the grill at a restaurant, or in your lunchtime frozen entree. This happens by osmosis: water moves from a salty marinade into the cells of the meat so that there’s more juice in the meat when it starts cooking. Since liquid escapes in the cooking process, using a salty marinade results in juicier meat. Salt is also used as a preservative in many foods, such as deli meats, hot dogs, and soy sauce,
controlling the growth of harmful bacteria. And of course food manufacturers add salt to make food taste better.

Without salt, many food products would be unrecognizable. This was dramatically evident when a
New York Times
writer attended a rather unusual tasting at Kellogg’s laboratories in Battle Creek, Michigan:

As a demonstration, Kellogg prepared some of its biggest sellers with most of the salt removed. The Cheez-It fell apart in surprising ways. The golden yellow hue faded. The crackers became sticky when chewed, and the mash packed onto the teeth. The taste was not merely bland but medicinal . . . They moved on to corn flakes. Without salt the cereal tasted metallic.

Salt clearly serves a superhero role in some packaged foods, but the food industry’s reliance on salt goes way beyond functionality. In some cases, the overreliance on salt is unwarranted. Adding salt makes product formulation easier, even in products where salt isn’t used for its preservative effect. Salt is also cheap, so it’s a way to add more flavor without having to add more of the expensive ingredients that give food its characteristic flavor, such as meat, vegetables, cheeses, or herbs.

Let’s take canned and frozen foods as an example. There’s absolutely no role that salt plays in canned foods, other than to make them taste better. The same is true of most frozen foods, with the exception of the moisture-holding property that salt gives to proteins like chicken and beef. Canning and freezing eliminate most of the need to use salt as a preservative. The salt problem in the food industry is a “catch-22” at this point. Americans are used to very salty food, so the industry has to deliver upon this expectation or consumers won’t buy their products. The result is that we’ve all just gotten comfortable in this salty laziness. Salt doesn’t require you to think too much about what you’re eating. Salt is salty and that tastes good. Now, on to the next bite.

The evolutionary elegance of our craving for salt has become a public health issue in industrialized countries where people don’t sweat enough—due to lack of physical exertion—but still crave salt as our caveman ancestors did. The result is that we eat far more of it than we lose, the opposite of Beth Goldstein’s cycling predicament. Overconsumption of salt can lead to high blood pressure and other health problems.

If you eat a lot of salty foods, the sodium from the salt enters your bloodstream, pushing your fluids to the edge of normal function. To even things out, your body begins dumping water into the bloodstream, trying to maintain that narrow range of sodium. This extra volume swells your veins and arteries, making everything move a little faster. The result is that your blood pressure goes up.

Americans now eat far more salt than they used to, and more Americans have high blood pressure. The idea that the former trend is causing the latter makes so much intuitive sense that many scientists have accepted it, even though large-scale trials and epidemiological studies that attempt to link high salt intake to high blood pressure have shown mixed results. Any epidemiological study, in which you are looking at a disease in a lot of people, is complicated (or confounded, to use the technical term) by all the ways that each of those people is different—this one eats lots of salt, but sweats it out all day; another eats lots of salt but doesn’t sweat. In addition, controlling our blood pressure is not a simple mechanism with salt on one side and water on the other. It’s more like a system of dams, canals, and pipes that controls the movement of snowmelt from the mountains, through farmland, into cities, and finally to your tap. Blood pressure depends not just on sodium, but also on potassium (which constricts or relaxes blood vessels), calcium, sugars, and hormones.