Sometimes when I crack a bottle of screw-top red wine I immediately put the cap back on instead of letting the wine breathe. I figure screw top indicates that the wine is "ready to go" and doesn't need to catch a breath. True?
Au contraire. If I were you, I'd let that bottle breathe. Screw-cap wines generally benefit from more aeration, not less, than cork-sealed wines.
Exposure to oxygen imparts two key benefits. Mainly, it helps soften the texture and enhance fruity flavours. Decanters are designed specifically for this purpose, with wide bowls to maximize the wine's surface area as it sits on the table. Young wines as well as old, whites as well as reds, can improve with air contact over a few hours (beyond about eight hours a wine can start to fade). Yes, this applies even to wines that are "ready to go." Not that you need to go out and spend a bundle on a decanter to enjoy wine. Just pour and go; it should taste good regardless.
Aeration also can rectify a wine flaw that's most commonly encountered with screw caps rather than corks. It's called hydrogen sulphide, an unpleasant odour that can reek of rotten eggs. The chemical, though harmless, can be produced during fermentation, typically by yeasts that have been starved of energizing nitrogen. If the winemaker is not on top of the situation, H2S becomes trapped in the bottle. Corks are slightly porous, so they permit the compound to escape over time, usually before the wine reaches the table. Screw caps, on the other hand, are much less forgiving. The H2S can't escape. So, when you twist open the seal, you might detect an unpleasant odour. In extreme cases, the wine can smell of sewer gas.
Because H2S is highly volatile, it blows off rather quickly after the seal is broken. If you smell rotten eggs, don't recap the bottle. Let the wine breathe for a couple of minutes or slosh it around in your glass. All should be well.
E-mail your wine and spirits questions to Beppi Crosariol. Look for answers to select questions to appear on The Globe and Mail website.