Taste: Surprising Stories and Science About Why Food Tastes Good (33 page)

Jennifer Stamps wants to do research on professional chefs in the future. She has a theory that they do not get dementia as frequently as others because they’re constantly using their senses of taste and smell. She thinks that rigorous use of their olfactory sense, in particular, keeps their brain in shape, like a muscle: if you don’t use it you lose it. She also believes that people who eat the same thing every day, like her grandfather, aren’t building new olfactory cells. By eating more varied, new foods, you challenge your brain, keeping it young. Her grandfather died of a neurological disease and she’s convinced there’s a connection. If eating a varied diet with thrill-seeking abandon is a way to stave off senility, then I say bring on the nutria.

I
t’s tomato season as I write this, my favorite time of year. There are only a few months of this ecstasy, when the tomatoes are pregnant with juice, thick-skinned, and calling to me from every grocery store, farmers’ market, and restaurant menu. My father was a backyard tomato gardener and we ate them every night during the summer. On Sunday he’d fry slices of them with a crispy breadcrumb coating. They are one of the flavors of my childhood.

For forty-some years, I’ve been salting my fresh tomatoes. In my youth, I sprinkled Morton’s iodized salt on them, as my dad taught me to do. Later, I added cracked black pepper. I went through a brief phase of dousing them with balsamic vinegar. In the early 2000s I discovered sea salts in all hues, crystal sizes, and flavors. In the past year I’ve been treating myself to a drizzle of tree-fresh olive oil from our friends’ grove with freshly ground salt, my current favorite being Himalayan Red Mountain.

But this year I decided I was going to go through tomato season without salting my tomatoes. When you get used to eating a food one way, you become accustomed to that preparation
.
I was so accustomed to salted tomatoes that I thought of them as a single flavor, fusing them in my brain as I do buttered popcorn
or milky chai tea. I never ate one without the other, so I never really gave much thought to their individual flavors.

Eating an heirloom tomato without salt was like getting intimate with a former lover for the first time in years. I knew the curves and contours of my tomato, but I never realized just how beautiful it was naked. Its forgotten perfume aroused my sense of smell: a whiff of earth, a sniff of vegetal, and a dash of musty vine. The height-of-the-season sweetness made the juice softer, less acidic. And the ripe, red flesh was full of free glutamates, which mean savory umami goodness. I was in love again with something I eat almost every day.

Yet my affair with the naked tomato lasted only about three weeks, after which I returned to salting. I was simply too weak—or is it that salt is simply too good? I really wanted to believe the latter, so I went to the experts with one simple, straightforward question. Why does salt make food taste so much better?

As always, the answer is complicated and long—unlike tomato season, alas.

We use the word
salty
to refer to the taste of many foods. But the prototypical pure salt Basic Taste is the compound called sodium chloride. This is the stuff we know of as table salt.

Paul Breslin of Rutgers University has spent a lot of time studying salt. According to Breslin, the sodium part of sodium chloride is what makes salt taste salty; the chloride part of it “enables the sodium to do its thing.”

What that
thing
is, though, is still a mystery. “We don’t know how salt taste works,” Breslin says, meaning that we don’t fully understand how it works at the microscopic level of the taste receptors within our taste buds. Scientists are working to identify the salt receptor. Nonetheless we do know how salt works to make things taste better.

The short scientific reason why I caved in so easily is that salt actually makes savory foods such as tomatoes taste better.

“Something that is purely salty and something that is purely umami [savory]
won’t taste nearly as desirable as the combination of the two together,” says Rutgers’s Paul Breslin. Tomatoes are high in the umami Basic Taste, so the sensory input from the combination of savory tomato flavor and salt is greater than the sum of its individual parts. This has been proved for many different foods. We consider a chicken soup more chicken-y if it contains salt than if it does not. The challenge in cooking and seasoning food is to heighten the savory flavor of the chicken without going overboard on the salt. Chef Joshua Skenes of the restaurant Saison in San Francisco perfectly captures the challenge in using salt to bring out other flavors.

“We look at salt not as something that you can just throw on food to make it taste good, but as something that pulls the flavors and extracts the flavors from food. You don’t want to taste salt,” he says, “you want to taste the ingredients. You want to salt the food so that you can taste the most natural purity of the flavor in the food to the fullest possible extent but
not taste the salt.
”

This was exactly what I was doing by salting my tomatoes. I was not looking to taste the Basic Taste salt. I was simply looking for more tomato flavor, which was partly achieved by salting, since that makes the umami Basic Taste more intense.

The simplest way salt works is that salt tastes salty and we innately crave this taste. The reason we crave salt is simple, and actually quite elegant. We have evolved to crave salt to ensure that we eat enough sodium to sustain life. A mineral that’s found in many places in nature, including human cells, sodium is essential to regulating the water balance in cells, and plays a role in nerve and muscle function. Our bodies generally maintain the perfect amount of sodium in our blood, which is such a narrow range that you’d think a micromanaging accountant was checking on the numbers every day. If the sodium level in our body gets too high or too low, the kidneys and heart bring it back into range. This balancing act is done without a backup reserve of sodium for times when we might need it, and we are constantly losing salt through urine, feces, sweat, and tears, which (hopefully) you shed only from joy. Without a way to store excess sodium in our bodies, we have to make sure we get it from the foods we eat or drink. The result of losing too much sodium can be death.

A person who is severely dehydrated thirsts for water so desperately that he
will drink whatever is available. People who are lost at sea drink seawater (which we dislike and which further dehydrates us) and urine (which disgusts us). But if you are deprived of salt, you will not crave salt in the same way a person with a life-threatening thirst demands, hallucinates about, and obsesses over water. Humans clearly have an appetite for salt, seeking it out in all types of food, but this is different from salt hunger, which could save our life by making us crave salt in situations when we need it. For some strange reason, we don’t read our bodies well enough to know when we’re dying from salt depletion.

Why do we not hunger for salt when the sodium balance in our body is out of whack? Your craving for salt is affected when you’ve lost sweat from exercise. Your sweat contains sodium, which means that salty foods and drinks will taste more palatable than before you exerted yourself. Even so, you won’t spontaneously reach for the salt shaker to replace this loss. You will simply drink and eat food, some of it containing salt, some not, until your body is back in balance. Human survival depends more on getting water than it does on getting salt. So we crave water first and salt second. Sometimes this is the very problem that gets us in trouble.

A decade ago, Beth Goldstein was pedaling her bicycle across South Dakota as part of a cross-country trip. When Beth sat down to eat in those days, she vigilantly corralled her appetite. A strict vegetarian, she ate only what she thought was healthful. Naturally lithe and athletic, she gloried in the effect that hard cycling had on her body.

“I would see some of my teammates eating huge roast beef sandwiches and fighting over the horseradish mayonnaise sauce—fighting over all this stuff that just seemed disgusting to me. So I’d make myself a little sandwich and I would have a cookie—I avoided the stuff that seemed greasy and the stuff that looked like it would make me feel thirsty. So I wasn’t eating potato chips or anything—I think in general I wasn’t eating as much salt,” she says, recalling the event.

On the Fourth of July they were riding through rolling farmland outside Pierre, South Dakota. “I was thinking,
Wow, it’s a hot day, there’s not a lot of shade, I should really drink a lot of water
,” Goldstein remembers. In fact, this was a terrible mistake: her body was already low on salt, and each sip of water further diluted her blood. Her body was trying to keep her fluids at a safe concentration
of saltiness, working overtime to sweat out the water. Unfortunately for Goldstein, sweating also carries some salt out of the body, so the more she sweated, the more salt she lost. Of course, she could have solved this problem if she had eaten a handful of salty nuts or potato chips every so often.

Goldstein was burning a lot of calories, but if she had any specific cravings, she dismissed them so brusquely that she does not even remember them today. She laughs. “I wanted to think of myself as a healthy person who was getting healthier, so I shouldn’t eat unhealthy food.” Salt, in her mind back then, was unequivocally unhealthy. “It was dumb. I should have been eating as much as I possibly could have.”

Looking back, Goldstein realizes that in the final stages of the ride on the Fourth of July, she must have been delirious. She was screaming Bob Marley songs at the top of her lungs, and laughing hysterically over nothing. When they reached that night’s stopping point she felt light-headed. Everything began to feel a bit distant. “Like you were watching your life on TV,” she said. The basic operations of her brain, the handoffs of electrical charges from receptor to neuron, were beginning to fizzle and fail. Yet because it isn’t unusual for a cyclist to feel a little off after a long day, Goldstein assumed she was dehydrated. Even though she wasn’t hungry or thirsty, she forced herself to drink at least four quarts of water. Hydration is good, she kept telling herself. Then she started shivering.