The New York Times recently had a good article about the chemical reactions that cause flaws to disappear and tannins to soften, as well as gadgets sold to effect these changes. I am usually skeptical of both wine gadgets and conventional wine wisdom on this subject.
Wine folks do things like opening bottles and letting them sit for hours in the hopes of letting oxygen enter and cause a reaction that softens the tannins. We call it “letting the wine breathe.” How it breathes through that little hole and just the small amount of wine that the air can touch has always been beyond me, but I still do it now and then.
But Mr. Waterhouse maintained that no brief treatment could convert the tannins to less astringent, softer forms, not even an hour in a decanter.
“You can saturate a wine with oxygen by sloshing it into a decanter, but then the oxygen just sits there,” he said. “It reacts very slowly. To change the tannins perceptibly in an hour, you would have to hit the wine with pure oxygen, high pressure and temperature, and powdered iron with a huge catalytic surface area.”
So why do people think decanting softens a wine’s astringency?
“I think that this impression of softening comes from the loss of the unpleasant sulfur compounds, which reduces our overall perception of harshness,” Mr. Waterhouse said.
I always suspected as much, but had never seen anyone debunk conventional wisdom in quite that way. There are a lot of other pearls of wisdom in the article that fly in the face of common knowledge.