Tag Archives: wine

What’s Up With That: Why Some Wines Taste Better With Age | WIRED

What’s Up With That: Why Some Wines Taste Better With Age | WIRED.

A finely aged wine is the result of a drastic molecular transformation.

Imagine you have two glasses of wine in front of you. Each was made from grapes grown on the same vines, but 10 years apart. The glass on the left is young, smells like ripe berries, and when you take a sip it fills your mouth with tart bitterness. You swallow, and your mouth feels dry and slightly chalky. The glass on your right smells like earth and leather. The fruitiness is still there, but its taste is more subtle, and mixed with chocolate, licorice, and leather. You swallow, and your mouth feels fuzzy and warm. The flavors taper off slowly.

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A bottle of wine might look like a closed system, but inside there are complex chemical transformations that scientists are still unraveling. However, there is wide agreement that the most critical factor in the aging of wine are tannins.

Tannins are a group of molecules that come from grape stems, seeds, and skins. “Tannins are present in all grapes and are generally produced by the plant as defensive compounds,” said Jim Kennedy, an enologist at California State University, Fresno. Tannins have anti-fungal properties, but also make the unripe grape taste really nasty until the seed is mature. Not only do they taste bitter, tannins bind to the proteins that make your saliva slimy, stripping away the sliminess, leaving your mouth feeling dry, chalky, and ashen. “This is like how a green banana leaves your mouth feeling,” Kennedy said. This feeling is called astringency.

But tannins aren’t just salivary spoil sports. They’re also indirectly responsible for a wine’s smell. Tannins don’t have any aromas themselves, but react with the wine’s alcohols and esters (acidic alcohols) to gradually subdue the flowery, fruity aromas of youth. They also combine with other molecules to help create the more complex and subtle smells characteristic of mature wines.

Small amounts of oxygen leaking in through the cap react with the tannins, helping prod along its chemical transformations with other molecules. But, if that oxygen comes in too quickly, it will overwhelm the tannins and oxidize the other molecules, causing the wine to taste skunky (similar to how an exposed apple turns brown). The wine’s acids are preservatives, and help buffer against this rapid oxidation, giving tannins time to neutralize individual oxygen molecules.

Coping with unruly oxygen molecules alters tannins, says Kennedy, which affects the way the wine will eventually feel in your mouth. Instead of binding with salivary proteins and leaving your mouth dry, mature tannins (along with those maturely scented molecules they’re bound to) linger pleasantly on your gums, cheeks, and tongue. (If you’re interested, Wineanorak.com has a full scientific breakdown of what scientists currently know about tannins.)

The winemaker determines the amount of tannins that go into the wine, primarily by controlling how long the mashed grapes stay in contact with the tannin-loaded stems, skins, and seeds. Wine that’s allowed to marinate at length in the grape detritus will start out as a bitter, dry youngster, and mature into a rich, complex, and highly desirable vintage. Wines that age well do so over a continuum, and there is an ideal period where the flavors of both youth and maturity are balanced. “You will have a little bit of youthful fruitiness and some of the bottle bouquet,” says Andrew Waterhouse, an enologist at UC Davis. Opening a bottle when it’s at this peak is highly desirable, but hard to do.

Tannins also affect the color of the wine. “The bluish-red color of a young wine is all due to pigments in the grape,” Kennedy said. “Those initial plant derived compounds go away after a couple of years.” They are gradually replaced by deeper, brick-red colors created as long polymer chains that link the grape pigments to the tannins.

Most wines that age well are reds (their color comes from the long exposure to skin, stems, and seeds), but only certain grapes have the right balance of sugars, acids, and tannins to support a long aging period. Typically, these tend to be grapes grown in places with long, warm summers and cool, but not frosty, winters. California’s Napa Valley, or France’s Bordeaux region are both known for wines that age well. Some of the more popular grape varietals for aging are Cabernets, Merlots, and Malbecs, Waterhouse says.

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What’s Up With That: Why Toothpaste and Pine Nuts Can Make Some Foods Taste Disgusting | Science | WIRED

What’s Up With That: Why Toothpaste and Pine Nuts Can Make Some Foods Taste Disgusting | Science | WIRED.

Miracle fruit.

What’s up with things that alter our sense of taste? Why does orange juice taste revolting if you drink it too soon after brushing your teeth? Or how about sipping white wine after eating artichokes? For some people, that makes the wine taste weirdly sweet. Even more bizarre are the berries of the so-called miracle fruit, Synsepalum dulcificum, which make even sour lemons taste sweet.

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Some scientists are even trying to exploit such taste oddities to make healthier foods that trick the brain into thinking it’s getting something more delicious than it really is. Linda Bartoshuk, an experimental psychologist at the University of Florida, and her team have been investigating naturally occurring volatile compounds in fruit that make foods taste sweeter or saltier by influencing how the sense of smell and the sense of taste interact in the brain. “Those interactions are much more interesting than we ever dreamed, and they may lead to new ways to add sweet and salty taste to foods without actually adding sugar or salt,” Bartoshuk said.

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Miracle fruit

In tropical West Africa, berries of the shrub Synsepalum dulcificum (photo above) were traditionally used to sweeten palm wine and make stale bread more palatable. More recently they’ve been used in Queens at “flavor tripping parties” where people do vinegar shots and say things like “Doughnut glaze, hot doughnut glaze!” after someone puts Tabasco sauce on their tongue.

The secret to this freaky fruit is a chemical called miraculin. It’s a protein with sugars attached to it. Normally these sugars don’t activate the sweet receptors on the tongue; they are like a key that doesn’t quite fit the lock. That’s why miracle berries on their own don’t taste particularly sweet. But in the presence of vinegar, lemon juice, or other acids, the molecule changes shape in a way that allows it to fit the sweet receptors and trigger the perception of sweetness. (It’s also possible the receptors themselves change shape—scientists haven’t yet worked out all the details). “It adds an intense sweet taste and in turn suppresses the perception of sour in the brain,” Bartoshuk says. The effect can last an hour or two—plenty of time to eat enough strange things to give yourself a serious bellyache.

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Artichokes

Artichokes are notoriously hard to pair with wine. You’d think they’d go well with whites, but for many people they make wine (or other beverages) taste unusually sweet. Whether that’s good or bad depends on your perspective.

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In a 1972 paper in Science, Bartoshuk identified the compound responsible for this effect. It’s called cynarin, and unlike miraculin, it doesn’t require acid to work its magic. It makes even water taste sweet. Again, the cellular-molecular details are a bit murky, but Bartoshuk says what seems to happen is that cynarin temporarily inhibits sweet receptors. Then, when you wash off the cynarin by taking a drink, the receptors bounce back and fire, sending a signal to the brain that they’ve detected something sweet.

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Orange juice and toothpaste

Scrubbing your teeth before breakfast is a bad idea for lots of reasons, but if your breakfast includes orange juice it’s even worse. The normally delicious sweet-tart juice will taste bitter and awful.

The chief culprit is probably sodium lauryl sulfate, a detergent added to many toothpastes to increase foaming and make your mouth feel clean. “The detergent tends to reduce your ability to taste sweet, and whenever you encounter any type of acid, there’s a bitter taste that’s very unpleasant,” Bartoshuk said. The most likely explanation at the molecular level is that the detergent alters the responsiveness of taste receptors by disrupting the fatty membranes that enclose each cell (much as dish detergent would break up the oily layer atop a sink filled with dirty dishwater).

Pine nuts

What do you do when one of your favorite ingredients suddenly turns against you? For some people, that’s what happened with the emergence of “pine mouth,” a mysterious syndrome in which eating pine nuts causes an unpleasant bitter or metallic taste that starts a day or two later and can last for a week or more.

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One species in particular, Pinus armandii, a white pine from China, has been linked to “pine mouth.” According to one report, a poor pine nut harvest in 2010 resulted in Chinese imports accounting for up to 80 percent of pine nuts sold in the U.S. that year, coinciding with an uptick in reports of pine mouth.

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The culprit could also be a contaminant or something used to process the nuts, Pelchat adds.

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So far, scientists can only guess at the mechanism, and some of those guesses are kind of creepy. One idea, suggested by Bartoshuk, is that the metallic taste is a phantom caused by nerve damage, essentially a taste equivalent of the phantom limb experience of some amputees. The nerves that carry taste signals to the brain inhibit one another, she explains. Damaging one nerve releases inhibition on the others and can cause phantom taste sensations. Indeed, she notes, a metallic taste is a common side effect of damage to the chorda tympani nerve. This nerve passes through the middle ear on its way from the tongue to the brain, and it can be damaged by surgery or infections of the middle ear. So far, though, no neurotoxic agent has been identified in pine nuts.

Another idea, proposed by Gregory Möller, a Professor of Environmental Chemistry and Toxicology at the University of Idaho, is that the metallic taste arises, at least in part, not in people’s mouths, but in their guts. The small intestines have bitter receptors similar to those on the taste buds, and some pine nuts may contain compounds that either stimulate those receptors directly or by prompting the production of bile,

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We smell things in the air around us by sniffing with the nose. But when we eat, there’s an additional pathway involved. “When you put food in your mouth and chew it up, the aroma from the food is forced up behind your palate and into your nasal cavity from the back,” Bartoshuk explains. “That’s called retronasal olfaction.” She thinks retronasal olfaction has a bigger impact on our perception of taste than the regular old route through the nose.

Her group has been studying this effect in tomatoes and strawberries. They’ve found, for example, that people perceive tomatoes of one variety, Matina, as twice as sweet as another, Yellow Jelly Bean, even though the sugar content of Matinas is actually lower. The reason, Bartoshuk says, is the mix of volatile compounds in each strain. She says her group has identified more than 80 volatile compounds that alter the perception of sweetness and saltiness via retronasal olfaction. Most have only modest effects on their own, but they have much stronger effects when combined. Bartoshuk thinks it should be possible to exploit those effects to create healthy foods that taste better.

Our brains evolved to crave sweet, salty and fatty foods because our ancestors needed to gobble up energy and nutrient-rich foods when they found them, Bartoshuk says. That’s why it’s so hard to change people’s behavior with education alone. ‘If we want people to get healthier, we can either keep trying to educate them, or we can find ways to make food taste the way evolution makes us want it to taste,” she said.