research - Why we smell wine by Jon Bonné

Swirling and sniffing 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.