By Robert L. Wolke
Wednesday, April 25, 2007
I have been drinking green tea for about four years, ever since I concluded that the hundreds of scientific studies on whether it lessens the risk of cancer and heart disease all boiled down to one phrase: "more likely than not." The latest research only strengthens that conclusion. How has green tea earned its reputation? By virtue of its large amounts of antioxidants.
Real tea is made from the leaves of a single plant, Camellia sinensis. ("Herb teas" such as chamomile and its ilk are not tea at all; they are infusions of virtually any plant material the natural-food folks can come up with, apparently excepting only hemlock.) When picked, some tea leaves are allowed to oxidize (a natural process that almost everyone mistakenly calls "fermentation"). Their tannins, or polyphenols, turn dark, and the result is called black tea. Tea that is only partially oxidized and therefore lighter in color is called oolong.
But if the leaves are first treated with hot steam, the enzyme needed for oxidation is deactivated, and the result is green tea. White tea is made from the silvery buds and new-growth leaves of a special varietal tea bush and, like green tea, is not oxidized. Unless specifically labeled green, white or oolong, all the teas in your supermarket are black.
Green tea's main brand of antioxidants, the catechins, fight harmful oxidants in the body known as free radicals. Catechins make up about 30 percent of the weight of each dried green tea leaf. White tea contains comparable amounts, but black tea retains very little.
I mistrust tea bags (what are they trying to hide?), so I've been drinking a loose green tea called Temple of Heaven Special Gunpowder (tightly rolled leaves that resemble gunpowder pellets) from China at $2.49 for a 500-gram (18-ounce) box. But there are so many kinds of green tea out there that I decided to try some others and to vary my brewing method until I found what I liked best. I recommend such experimentation to anyone who is drawn to green tea's antioxidant qualities but has found that the taste isn't exactly their, um, cup of tea.
The conventional wisdom is that a teaspoonful or so of green tea leaves should be steeped for about two minutes in one cup of 175- to 185-degree water. But that's not chiseled in stone. Only the water temperature is critical; the boiling-hot, 212-degree water customarily used to brew black tea would extract too many harsh compounds from the delicately flavored green tea leaves. The amount of leaves and the steeping time, however, can be whatever suits your taste.
A couple of weeks ago I discovered Teaism ( http://www.teaism.com), a shop in Washington that sells about three dozen kinds of Asian tea. With "so many teas, so little time" reverberating in my brain, I chose two premium green teas -- one Chinese and one Japanese (all Japanese tea is green tea) -- to compare with my old Gunpowder standby. They are Dragon Well, from China's Zhejiang province, and Genmai Cha ("cha" means "tea" in Japanese), from Japan, at $5.25 and $8.75, respectively, for a two-ounce (57-gram) package. Would they be worth the price?
Back home, I brewed samples of each tea in my single-serving mug fitted with a fine-mesh infuser basket. The drill was to put a measured amount of tea in the basket and the basket into the cup, then pour in eight ounces of 175-degree water.
I varied both the amount of tea leaves and the steeping time, recording their effects on drinking qualities as determined by a hastily assembled team of tasters consisting of my wife and me. Okay, so this wasn't the most scientific experiment I have ever done, but it taught me a few things.
I had always made my Gunpowder tea by steeping about two grams for about two minutes, which is the most widely recommended method. But in my experiments, I used amounts of tea from two to four grams and steeping times from two to four minutes.
Teas vary from very small leaves or pellets to large leaves; lacking a scale, one can figure that two grams will be about a teaspoon of small leaves and a tablespoon of large ones.
The results? The Gunpowder had the most body and flavor, with a good amber color and moderately strong tannins or astringency. I discovered that I preferred it at three grams of leaves infused for four minutes, which makes a much stronger brew than what I had been drinking.
The Dragon Well was bland and insipid at any strength. (Then again, no green tea can compare in body and color with a black tea, whose oxidized tannins are darker and more flavorful.) The Genmai had a pleasant, strawlike aroma and a nutty, toasty flavor that was quite pleasing at all strengths.
But not pleasing enough, especially at the higher price, to get me to abandon my good old Gunpowder, especially now that I know how to brew it to my taste.
So if you want to get on the green tea bandwagon, try several brands at several strengths, and pay no attention to "the rules": Except for the water temperature, there are none.
Robert L. Wolke (http://www.robertwolke.com) is professor emeritus of chemistry at the University of Pittsburgh and author of "What Einstein Told His Cook: Kitchen Science Explained" (W.W. Norton, 2002). He can be reached firstname.lastname@example.org.