How do apple, butter and vanilla flavors get into Chardonnay?

Have you ever seen the book Wine for Dummies? Well, here's a confession. I'm one of those dummies.

Maybe that's an overstatement. I do know a thing or two about wine: it can have a big nose; it can be dry as a bone; it can be flabby or lean, earthy or floral, jammy or grassy. But what do all those wine words mean? Sure, I'm able to swirl a glass of Cabernet without baptizing the tablecloth, but ask me to describe what the Cab tastes like and I'm Charlie McCarthy without Edgar Bergen. I take a sniff and a sip, then send an urgent request for information to nose, tongue and brain. They respond grudgingly: the wine tastes Not the answer I was hoping for.

It's time to give my senses a wake-up call. I ask Rory Callahan for help.

Callahan, president of Wine & Food Associates in Manhattan, has the shy but eager air of a scientist who spends a lot of time alone in his laboratory. As a young man, in fact, he worked as a biochemist before he fell in love with wine, hung up his white coat and entered the enology program at the University of California at Davis. He has directed wine studies at New York University and has also worked on marketing projects for clients like the New Zealand Wine Institute, Wines from Spain, and the Sonoma County Wineries Association.

Callahan's science background may explain his enthusiasm for a particular type of wine lesson, called a sensory, or component, tasting. The goal is to demystify wine by isolating some of its most basic elements. He's agreed to take me on as a student: Henry Higgins to my Eliza, Mr. Kotter to my sweathog. By the end of our session, he promises, I'll be a lean, mean tasting machine.

Tutoring My Taste Buds

"Concentration is 90 percent of the battle in wine tasting," Callahan says when we sit down. I put on my best honor-student look and watch closely as he mixes a half teaspoon of sugar into a glass filled with about four ounces of water. "Sweet is one of the four basic tastes," he explains. (The others are sour, bitter and salty, though salty isn't much of a factor in wine.) "People often confuse sweetness and fruitiness when they're talking about wine, but sweetness is totally a tongue thing and fruitiness is totally olfactory." He's right. I sniff the sugar water--nothing. Then I take a sip and get a tingle on my tongue.

Sauternes, Muscats, and wines labeled "late harvest" are all sweet, with sugar levels higher than half a percent. A dry table wine, on the other hand, will typically have a sugar content below that threshold. (Fun fact: Since many Americans prefer wines with a touch of sweetness--"people talk dry but buy sweet," Callahan notes--some California wineries leave a trace of sugar in their Chardonnays.)

"Let's move on to fruit acids," says Callahan. "Acids protect a wine from microbes as it ages. A wine that has a nice acidity also tastes better and goes better with food."

I watch Callahan add a quarter teaspoon of white powder to a fresh four-ounce glass of water. The powder is sour salt, or citric acid, available at most supermarkets. (Fun fact: If you've oversalted a dish, sour salt can save the day.) I sip the sour-salt brew and immediately pucker up, plus my mouth starts watering like crazy. "Wow, sour," I remark sagely. "This is like lemonade without the lemon flavor or the sugar." Callahan nods, then issues a warning: "Never use the word sour as a synonym for acidic when describing a wine; you'll hurt the winemaker's feelings. Calling a wine sour is like saying it's vinegary. Instead, use words like crisp, lively or tart." I'll show off my new and improved vocabulary the next time I drink Sauvignon Blanc, one of the tartest wines.

"Last but not least, tannins," Callahan proclaims. Tannins--compounds that protect red wine from oxidation--offer both a tactile and a taste sensation. To demonstrate, Callahan prepares a tepid cup of Lipton tea for me. Tea tannins can be more bitter than grape-skin tannins, but their effect is similar and especially pronounced when the tea is brewed strong and allowed to cool.

Callahan fishes a tea bag out of the rust-colored liquid and extends the cup to me. I reluctantly accept it (don't I already know what tea tastes like?) and take a sip, then another. Suddenly, I feel as if I've licked a chalkboard. "As the tannins bind with the proteins on your tongue, you'll start to get that astringent effect, that drying sensation," Callahan tells me, unnecessarily. I try to keep an intelligent expression on my face, but it's hard when my tongue keeps getting stuck to the roof of my mouth. Politely ignoring my plight, Callahan explains that tannins seep from the grape skins, stems and seeds that are tossed into the fermentation tank along with the juice. Since oak also contains tannins, a winemaker can bump up a wine's tannin level further by aging it in an oak barrel.

The most tannic wines are the "big reds": California Cabernets, red Bordeaux, Australian Shirazes, and Barolos and Barbarescos. "God forbid you drink one of these wines too young," Callahan says ominously. Fortunately, the harsh tannins soften with age. Among the commonly available reds, Beaujolais Nouveaus are the lowest in tannins, and most whites are low in tannins.

Educating My Nose

Now that I've given my tongue a workout, it's time to train my nose. This is a greater challenge, since there are only four tastes but thousands of aromas. To introduce me to this realm of the senses, Callahan mixes up different scent samplers, then lets me sniff and sip wines that highlight those components. Isolating individual aromas should sensitize me to a few potent wine flavors.

Callahan begins by opening a can of lychees, sold at Asian groceries, and adding a few of the ivory-colored nuts and some of the syrup to about two ounces of white Almaden. This unassuming wine, he explains, will provide a neutral backdrop to the powerful lychee aroma and release the smell better than water would. I swirl the liquid vigorously, cupping my hand over the top of the glass to concentrate the fragrance, and inhale. The smell is heavy, heady and lush, like frangipani.

While I sniff away, Callahan pours me a glass of 1996 Adler Fels Gewürztraminer from Sonoma. I lower my nose into the glass. There's that lychee aroma. "Lychees contain a compound called linalool, and so do Ge-würztraminer grapes," he explains. (Fun fact: Cosmetics companies use pure linalool for perfumes.)

I stop for a minute to admire my nose, which had always disappointed me as a sensory organ. Meanwhile, Callahan pours a glass of red Almaden--again, to provide a neutral backdrop--and slices four slivers of green bell pepper into the liquid. I take a sniff and get a hit of that pungent bell pepper aroma, somewhere between a new-mown lawn and a carnation. Then I try a 1995 Carmenet Dynamite Cabernet from Napa and Sonoma. Hello, bell pepper. Still, if my nose hadn't been sensitized to the smell, I doubt that I would have singled it out. "The compound responsible for this aroma is 2-methoxy-3-isobutylpyrazine, which tends to develop in Cabernet grapes from young vines grown in cool climates," Callahan explains.

To prime me for my next tasting--a pricey 1995 Far Niente Chardonnay from Napa--Callahan prepares three samplers of scent-spiked white Almaden: one with green apple slices, another with three drops of imitation butter flavor and the third with a whole vanilla bean scrunched up inside the glass. Flavor words I had once interpreted metaphorically take on literal meaning as I experience the Chardonnay's rich apple, butter, and vanilla notes.

The compounds that give green apples their flavor, says Callahan, are also present in Chardonnay grapes. But the butteriness develops via a winemaking technique called malolactic fermentation, a process that converts harsh malic acid into softer lactic acid. A by-product is diacetyl, the compound that gives butter its flavor. As for the vanilla, that comes from aging wine in oak. Many kinds of oak contain the compound vanillin, which leaches into wine as it sits in the barrel.

To wrap up our tasting, Callahan mixes two more samplers. For the first, he grinds black pepper into a glass of red Almaden. I compare the fragrance to a 1993 Guigal Côte Rôtie from France, which also boasts that nasal-clearing black pepper aroma, as well as a hint of clove. In winespeak, that translates into spiciness. "This wine cries out for lamb and roast beef," says Callahan. That or its own slot on a spice rack.

Finally, we tackle the word berry, which seems to pop up in almost every Pinot Noir description. Callahan adds red raspberries to a glass of our workhorse red Almaden and pours a 1995 Saintsbury Pinot Noir from Napa. I sniff the raspberry sampler, taking care not to bump the berries, and sniff and sip the Pinot. Raspberries redux.

The lesson comes to a close. As I survey the array of glasses before me, I wonder if I'll remember everything I've just learned or whether, as Callahan suggests, I'll be motivated enough to repeat the session at home from time to time to refresh my sensory memory. I do, after all, have my very own pepper grinder, but my supply of imitation butter flavor and sour salt may be on the low side. When I go home, I'll check my cupboard--and guzzle the rest of that Pinot Noir with my senses at full throttle.