Decanting is one of those elements of wine service that remains mysterious and intimidating to many drinkers: Which wines need it? When should you do it? And how? Is it really even necessary or just a bit of wine pomp and circumstance?
Fundamentally, decanting serves two purposes: to separate a wine from any sediment that may have formed and to aerate a wine in the hope that its aromas and flavors will be more vibrant upon serving.
Older red wines and Vintage Ports naturally produce sediment as they age (white wines rarely do); the color pigments and tannins bond together and fall out of solution. Stirring up the sediment when pouring will cloud a wine’s appearance and can impart bitter flavors and a gritty texture. It’s not harmful, but definitely less enjoyable.
Decanting is simply the process of separating this sediment from the clear wine. It’s fairly safe to assume that a red will have accumulated sediment after five to 10 years in the bottle, even if this can’t be verified visually, and should be decanted. Here’s how to do it well:
The question of whether—or how long—to aerate a wine can generate extensive debate among wine professionals. Some feel that an extra boost of oxygen can open up a wine and give it extra life. If you’ve opened a wine and it seems unexpressive upon first taste, it can’t hurt to try moderate aeration in a decanter to see if that transforms it.
Others feel that decanting makes a wine fade faster, and that a wine is exposed to plenty of oxygen when you swirl it in your glass. Plus, it can be fun to experience the full evolution of wine as it opens up in your glass; you might miss an interesting phase if you decant too soon.
A particularly fragile or old wine (especially one 15 or more years old) should only be decanted 30 minutes or so before drinking. A younger, more vigorous, full-bodied red wine—and yes, even whites—can be decanted an hour or more before serving. At some tastings, wines are decanted for hours beforehand and may show beautifully, but these experiments can be risky (the wine could end up oxidized) and are best done by people very familiar with how those wines age and evolve.
If you’re curious, experiment for yourself with multiple bottles of the same wine—one decanted and one not, or bottles decanted for different lengths of time—and see which you prefer.