At Last Some Sound Advice on Decanting To Aerate Wine
I started reading this article by Janet Fletcher in the San Francisco Chronicle with little enthusiasm as it looked like the same old same old.

Many wine professionals also say that decanting softens the tannins in red wine, achieving in a few hours what might take years to transpire in a cellar. Barolo and Barbaresco -- the big, brawny Nebbiolo-based wines of Italy's Piedmont region -- are almost always decanted, ostensibly to mellow the tannins and release the bottle bouquet.

But then came this. According to UC Davis Enology Professor Roger Boulton, there is absolutely no evidence that decanting produces any change in wine tannins, at least over a matter of days. Tasters may perceive that the tannins have softened, but laboratory tests show otherwise.

So that is another academic to claim that there is no science to support the argument that decanting softens tannins.

And then came this. Nor does oxygen play the role that many wine professionals think.

"If (a wine) seems a little closed in, the very best thing you can do is give it some oxygen," says Ronn Wiegand, publisher of the newsletter Restaurant Wine, articulating a belief echoed frequently by his colleagues.

But Boulton says oxygen has nothing to do with the aromas that emerge when wine is poured into a decanter or glass. The same aromatic bloom happens in a nitrogen environment, with no oxygen present.

Like a soda that releases some of its carbon dioxide when opened but retains some bubbles in the drink, bottled wine holds many of its aromatic compounds in solution with some proportion of them clustered in the headspace. When the cork is pulled and the wine poured into a container with considerably more headspace -- a decanter or a glass -- those aromas in solution, good smells and bad ones, have somewhere to go.

Some compounds volatilize more quickly than others; stinky sulfides and acetic acid are among the first to blow off, which is why the initial perfume may not be a wine's best. On the other hand, the esters responsible for the fruity aromas in many white wines also evaporate early, so decanting a Sauvignon Blanc or Pinot Gris may diminish its attributes.

Depending on the age of the wine and the aromatic compounds it contains, this release of aromas into the headspace might continue for two to three hours. But for the typical 10-year-old wine, says Boulton, an hour of breathing time should do it; after that, the wine is probably losing more good aromas than bad ones. And no matter how long the taster waits, a wine with the undesirable aromas of cork taint or brettanomyces, a spoilage yeast, will never lose them.

Nor does one need a decanter to unleash the aromas in a bottle of wine. "You and I can pour the wine from the bottle into the glass and do the same thing," says Boulton. "It's only if you're a sommelier that your role in the world is to pour it into a decanter."

Yes! (fist pump). Great stuff, could not agree more with his interpretation. But just to be sure I’m still working on an approach that will allow me to compare decanted and undecanted wine from the same bottle to see how much aeration does change a wine.

Final note: Interesting that “enjoyed the last glass more than the first” raises its ugly head in this article. I’ve seen this comment many times as a justification for decanting or aeration. I’ll bet there is no science to back up this claim. And if you think about the number of variables involved in comparing the first and last glass of any bottle you might come to realize that the comparison is truly meaningless.