What Einstein Told His Cook (27 page)

Much decaffeinated coffee today is made by a recently developed process that extracts the caffeine into familiar, harmless old carbon dioxide, but it’s in a peculiar form that chemists call supercritical; it’s neither gas, liquid, or solid.

Finally, there’s the ingenious “Swiss water process,” which washes the beans with hot water that is already fully loaded with all possible coffee chemicals except caffeine, so there’s no room for anything but caffeine to dissolve into it from the beans.

How does all this percolate down to your supermarket’s coffee aisle?

First of all, you may see the words
naturally decaffeinated
on the can. It may refer to the ethyl acetate method or it may mean nothing at all. Doesn’t everything come from Nature? What else should we expect?
Supernaturally
decaffeinated coffee?

Nor do the words
water process
mean much, because water is used in several methods, not just in the Swiss water process.

The best advice is to forget about the technology—they’re all safe methods—and choose your decaf on the basis of objective intellectual criteria, such as whether you’re more partial to Juan Valdez or Mrs. Olson.

TO TEA OR NOT TO TEA?

In a restaurant, I asked for hot tea and was presented with a box from which to choose any one of a dozen fancy kinds, including lapsang souchong, Darjeeling, jasmine, chamomile, and so on. How many kinds of tea are there, anyway?

O
ne. That is, there is only one plant—
Camellia sinensis
and a couple of hybrids thereof—whose leaves can be steeped in hot water to make real tea. They may have different names, depending, among other things, on where they were grown.

Some of those “tea” bags you were offered, such as chamomile, for example, do not contain tea. They contain various other leaves, herbs, flowers, and flavorings that can be steeped in hot water to make an infusion that is properly called a tisane, but that is also unfortunately known as an “herbal tea.” When you hear the words
herbal tea
, you’re supposed to think, Wow! Herbs. Natural. Healthy. Good. But you could make a tisane out of poison ivy leaves if you wanted to.

Real tea comes in three types, depending on how the leaves were processed: unfermented (green), semi-fermented (oolong), and fermented (black) by the action of enzymes, which oxidize tannin compounds in the leaves. Among the blacks, which are by far in the majority, you’ll find Assam, Ceylon, Darjeeling, Earl Grey, English Breakfast, Keemun, and Souchong. Any other names and you’re on your own; they may be real teas or they may be whatever someone thinks should taste good when soaked in hot water. The latter probably won’t kill you, but only real tea has withstood the test of time without any apparent ill effects except a British accent.

A (NOT-SO-) NICE CUP OF TEA

When I make tea with microwave-heated water, why doesn’t it taste as good as when I make it with teakettle water?

M
icrowave-heated water isn’t as hot as kettle-heated water, even though it may look as if it’s boiling.

Water for tea must be boiling hot in order to extract all the color and flavor. Caffeine, for example, won’t dissolve in water that’s much cooler than 175°F. That’s why the teapot—or if you’re a bag-at-a-time brewer, the cup—should be preheated, to prevent the water from cooling too much during brewing.

When you’ve got a full, vigorous boil going in a teakettle you know that all of the water is boiling hot—around 212ºF. That’s because the heated water at the bottom of the kettle rises, to be replaced by cooler water, which then becomes heated and rises, and so on. So the entire kettleful reaches boiling temperature at pretty much the same time. The bubbling further mixes it, to a uniform temperature.

But microwaves heat only the outer inch or so of the water all around the cup, because that’s as far as they can penetrate. The water in the middle of the cup gets hot more slowly, through contact with the outer portions. When the outer portions of the water have reached boiling temperature and start to bubble, you can be tricked into thinking that all the water in the cup is that hot. But the average temperature may be much lower, and your tea will be short-changed of good flavor.

Another reason that kettle-heated water is better is that heating a cup of water to boiling in a microwave oven can be tricky, if not to say risky (see p. 262).

WELL, TAN MY TONGUE!

What is the brown sludge that forms in my cup when I make microwaved tea?

P
atient
:
Doc, it hurts when I bend my arm this way.

Doctor: So don’t bend your arm that way.

My answer to your question is similar: Don’t make microwaved tea.

The water isn’t as hot as if you had used fully boiling water from a kettle. Thus, some of the caffeine and tannins (polyphenols) in the tea don’t stay dissolved; they precipitate out as a brown scum. Tannins are a broadly defined category of chemicals that give tea, red wine, and walnuts that puckering, astringent sensation in the mouth. They’re called tannins because they have historically been used to tan skins into leather. And that’s what they do, in a small way, to the “skins” of your tongue and mouth.

THE FIZZICS OF CARBONATION

A PHOSPHORIC FUSS

N
othing whatsoever. The article shouldn’t have generalized to that extent.

It’s a mistaken notion that all carbonated soft drinks are rich in the chemical element phosphorus (which almost everyone, it seems, wants to misspell as “phosphorous”). The only thing that all carbonated soft drinks have in common is carbonated water: carbon dioxide dissolved in water. Beyond that, they contain a wide variety of flavorings and other ingredients.

A few of them, including Coca-Cola, Pepsi-Cola, and some other colas (sodas containing the caffeine-rich extract of tropical kola nuts) do contain phosphoric acid. It’s a weak acid of phosphorus, just as the carbonated water itself is a weak acid of carbon: carbonic acid. All acids taste sour, and the phosphoric acid is there to increase the acidity and provide a bit more of a tang to set off the sweetness. Phosphoric acid is also used to acidify and flavor baked goods, candies, and processed cheeses.

About the bone-weakening effect: Maybe the study was limited to phosphorus-containing colas. Even so, just as one rose does not a summer make, neither does one study prove a cause-and-effect relationship between Cokes and bones.

THE BIG TANG THEORY

I have read that using powdered Tang in an empty dishwasher cycle will clean out all the soap scum and stains. I’ve also read that Coca-Cola will remove rust from a tennis net crank. What on Earth have we been drinking?

I
don’t know what
you’ve
been drinking, but there are plenty of riskier beverages out there than Tang and Coke. I’d be concerned about this particular duo only if my stomach were made of soap scum or rust. Just because a chemical does something to one substance doesn’t mean it’ll do the same thing to another substance. That’s what keeps chemists so busy.

It is undoubtedly the citric acid in Tang, Gatorade, and other fruit drinks that dissolves the calcium salts in dishwasher grunge. But it’s also citric acid that gives us that nice, tart…well, tang. Citric acid is, of course, a perfectly natural and harmless component of citrus fruits. You could probably clean your dishwasher as well by running it on lemonade.

The phosphoric acid in Coca-Cola can dissolve iron oxide (rust). There’s nothing special about tennis net cranks, however, except that their rust films are likely to be rather thin because of frequent use. I wouldn’t try to rejuvenate a rusty old lawn mower by throwing it into a vat of Coca-Cola.

A BURP IN THE BUCKET

Does belching contribute to global warming?

D
on’t laugh. That’s a good question. So good, in fact, that I thought of it myself when I learned that 15.2 billion gallons of carbonated soft drinks and 6.2 billion gallons of beer were consumed in 1999 in the United States. And what do you suppose happened to all the carbon dioxide in those beverages? It was ultimately released into the atmosphere by respiration and eructation—breathing and belching, to be plain-spoken about it.

On the traditional back of an envelope (scientists collect old envelopes for this purpose), I quickly calculated that 21.4 billion gallons of American beer and soda would contain about 800,000 tons of carbon dioxide. Wow! I thought, that’s one helluva collective burp. And that’s not even considering the chorus of harmonizing eructations from around the globe.

Why worry about carbon dioxide? It’s one of the so-called greenhouse gases that are acknowledged to be raising Earth’s average temperature. Granted, it hasn’t been easy to take the temperature of a planet. But modern scientific analyses are infinitely more sophisticated than stationing people on street corners with thermometers. Today, there is very little doubt that carbon dioxide and other gases produced by human activities have indeed been inching up the global thermostat.

Here’s how the greenhouse effect works:

There is a natural balance of energy between the radiations that shine upon Earth from the sun and those that are reradiated back out to space. When sunlight hits Earth’s surface, about two-thirds of it is absorbed by the clouds, the land, the sea, and George Hamilton. Much of this absorbed energy is converted—degraded in energy—to infrared radiation, often called heat waves. Normally, a significant fraction of these heat waves bounce back out through the atmosphere and return to space. But if there happens to be an unnatural amount of infrared-absorbing gas in the atmosphere—and carbon dioxide is a prodigious absorber of infrared waves—then some of the waves will never get out; they’ll be trapped near Earth’s surface and warm things up.

So should we all stop drinking soda and beer for fear of belching more carbon dioxide into the atmosphere? Luckily, no.

According to the Department of Energy’s figures for 1999, the last figures available at this writing, 800,000 tons of beverage-inspired carbon dioxide emissions amounts to 0.04 percent of the amount of carbon dioxide that was belched into the American atmosphere by gasoline-and diesel-burning vehicles. Our guzzling of carbonated beverages, then, is a mere burp in the bucket compared with our guzzling of gasoline.

So by all means keep on drinking. But don’t drive.

SLOW LEAK

My frugal sister-in-law buys her soda pop in large quantities at a discount warehouse club, and she claims that it’s often flat when she opens it. Can a bottle of soda go flat if it’s never been opened?

M
y first reaction was no, not if there isn’t a slow leak somewhere in the bottle’s seal. But after extensive research, which consisted of dialing the 800 Consumer Information number on a Coca-Cola label, I find that it is not only possible, it’s quite common.

After prompting the nice woman who answered the phone to enter the appropriate words into her computer, I eventually learned that plastic pop bottles (they’re made of polyethylene terephthalate or PET) are slightly permeable to carbon dioxide gas and that over time, enough gas can diffuse out through the walls to diminish the effervescence. That’s partly why—again to my surprise—many plastic soda bottles bear “drink by” dates on their caps. Glass bottles, of course, aren’t porous at all.

Classic Coke in plastic bottles, the woman said, has a recommended shelf life of nine months for optimum flavor and quality, whereas Diet Coke’s recommended shelf life is only three months. Why? “Try plugging ‘aspartame’ into your computer,” I suggested, whereupon after a few blind alleys we both discovered that the artificial sweetener aspartame is somewhat unstable and loses its sweetness over time.

By now we were having lots of fun with her computer, so I probed some more about what might affect the beverage’s quality. Freezing, the computer informed us, can lower the fizziness. That one was a challenge for me to figure out, but this is what I think may happen: When the bottle freezes, the expanding ice can bulge out the bottle, and when it thaws the bottle may retain its expanded shape. That makes more gas space into which more carbon dioxide can escape from the liquid, lowering its effervescence level.