Why we smell wine

We've all got wine questions, usually some we're afraid to ask. So this is the first of our answer sessions on wine. Let's applaud the brave souls who've volunteered to show what they don't know.

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Keep sending questions. There'll be more Q&As soon.

Brandon from Minneapolis writes: "My girlfriend is what you might call a wine snob. She's been in the restaurant industry for years and considers herself to be quite the aficionado when it comes to choosing wine when we go out to dinner which lately has become two to three times a week. ... I know nothing about wine! If something tastes good, I drink it and if it doesn't, I send it back. ...

"When the server comes out and pours a sample into her glass, she swirls the wine, smells the wine and then lets the server know if it's what she wanted. What the hell does the swirling and smelling have to do with the taste?"

First, Brandon — please, please, please tell me you're kidding about sending wine back.

There's only a couple legit reasons to send back wine in a restaurant. If they bring you the wrong wine, or wine that was somehow clearly mislabeled, send it back. If the wine they bring you is clearly ruined, send it back. (You need a pretty good sense of what the wine should taste like in order to do that.) If you're unsure whether it's spoiled, tell them what you think is wrong and ask them to taste it. A scrupulous server will know and will replace your glass or bottle.

Otherwise, you've got no more right to send back a wine you don't like than a pork chop if you decide you really wanted lasagna. You might have chosen something not to your taste — and we all do — but you ordered it, they brought it, and that's the end of the transaction. Sommeliers and bartenders are there in large part to help you pick something you'll like. If they're doing their job properly, they'll help you without making you feel foolish.

Now, as to swirling and sniffing, your girlfriend is right on. These are crucial, perhaps the most crucial, parts of evaluating wine.

We swirl wine to expose the actual liquid to the air, to run it up the sides of the glass and to get an extra look at its color. The drops, or tears, that trickle back down tell lots about alcohol content. The color of the wine, both when still and when swirled, gives hints to its density, the type and quality of the grape and the condition of the wine. New wine often has brighter hues than older wine.

Plus, some wine — particularly red wine — needs to oxidize slightly when opened. If it has been properly stored, little oxygen will have reached it. As wines age, they need air to help fully release their aromas and flavors. Swirling helps.

Why smell? A wine's real charm can be found in its scent. Here you can discern a wine's primary and secondary aromas. All those frou-frou descriptions about scents of huckleberries and roses? That's how we detect many of them. Smelling offers a preview of what you might taste, not just then, but also if you let the wine sit for a while and open up.

Indeed, smell and taste have been intricately linked in the brain, and much of the taste of wine (or food) is lost without the smell. Don't believe me? Try holding your nose and swishing some wine in your mouth. Then try it without holding your nose. See the difference.

Scent also helps detect if a wine is spoiled. If you're smelling damp cardboard or gym socks, there may be cork taint, the presence of a destructive little compound called trichloroanisole (TCA). That's what we mean when we say a wine is "corked."

There's lots more — books full, in fact — on why all these rituals are not just wine snobs showing off. Traditionally, in a restaurant, you're usually checking for any faults, not whether a wine is to your taste. (That should have been resolved when you ordered it.) You're figuring out whether to start drinking it immediately, or whether to ask for a decanter, which helps aerate it and filters out sediment in older wines.

Ask your girlfriend to walk you through the process next time. We'll lay even money she'll be glad you did.

Tom of Elizabethtown, Ky., asks: "I enjoy a merlot and an occasional zinfandel. Can you explain the makings of white merlot and white zin?"

An excellent question. One many of us would love to pretend we didn't need to ask.

White zinfandel or white merlot are made from the same grapes as their red counterparts. But the juice that ferments into wine is removed from the red grape skins before it absorbs much of the skins' flavors, tannins or red color, hence the blush pink tint and sweet white-wine taste. The very same process is used to make rose wines.

The wines are generally sweet because winemakers halt the fermentation process before all the sugar in the grape juice is converted into alcohol. Occasionally, some sweeter grape juice may be added to enhance the sugary punch. This residual sugar gives the wines their sweetness, which California winemakers in the 1970s and '80s found they could easily market to a mostly novice wine-drinking public. The sweetness contributed to these wines' reputation as mass-market swill, though the sometimes clunky flavors and often lower-quality grapes used in them is probably more to blame than anything.

Hence they're usually mocked by the majority of wine geeks (though some of them are enamored of heavily oaked wines that aren't much more subtle). Some of this is the mark of people who would never, ever admit that white zinfandel was their gateway into wine. In any case, the makers of blush wines seem perfectly content to indulge a very healthy market. If you look at wine sales in this country, wineries like Sutter Home (which pretty well invented white zin) are in no fear of Americans losing their taste for it.

Besides, we could all be drinking Zima.