Q: How long can I keep an open bottle of wine and still drink it? - Shannon, Massachusetts
How long does an open bottle of wine last? For me, under an hour. I jest! There's good news and there's bad news: The good news is that wine doesn't go bad in the way food does such that it can actually make you ill, but the bad news is that after just a day or two most opened bottles won't taste very good. It depends on what type of wine you have, and little bit on how you store it once it's open.
Once oxygen comes in contact with wine, the wine will begin to change as aroma particles shake themselves loose and other molecules mix and mingle.
While young, tannic red wines often need a few minutes - or even hours - in a decanter (which should be called an aerator in this case, but that's another post) to let that process enhance their aroma and flavor, most of the time exposure to air just gradually reduces a wine's flavor and aroma until so many of the tasty particles float away that it tastes flat and boring. For still wines, higher alcohol bottles tend to last longer than lighter bodied ones. Sparkling wines, even if you use a specially designed stopper, will lose their bubbles in a day. The overall exception to the couple-of-days rule are fortified wines, especially those that are deliberately oxidized during production as in Sherry or Madeira, because that oxidation combined with higher alcohol levels can keep them tasting the same for a week or even months after opening, depending on the style.
Personally, I don't think any of the various vacuum pump ding dongs marketed to consumers do much to preserve wine, and I have tried quite a few. So unless you're ponying up a few grand for an enomatic system, you might as well just stuff the cork back in and, whether it's a white or a red that you will need more than a day or two to finish, stick it in the fridge. Many a sommelier has told me this, we did it when I worked in bars, and at home I have found that popping bottles into the fridge keeps them going a day or two longer than you would otherwise expect. It doesn't hurt, anyway.
If you do find that your leftover wine has gone flabby on you, you can always cook with it or make vinegar. Freezing wine in an ice cube tray lets you store the cubes in a bag to use one at a time for sauces, which is pretty neat.
My best advice: Drink wine with friends, and you won't ever have these problems!
Got a question about wine or spirits? "On the Bottle" appears every Friday on the Martha Stewart Living Radio blog. Email your booze and wine quandries to firstname.lastname@example.org and they'll be answered in a future post.