The problem of leftover wine begs two questions: Is wine always best fresh, fruity and straight from the bottle? And, given the right tech, is it reasonable to keep an open bottle of wine indefinitely?
Some wines perform better when they’ve been decanted or left to stand in an open bottle. It all has to do with wine’s very complicated relationship with oxygen: Too little exposure dramatically slows wine’s evolution; too much rapidly degrades it. While reds tend to hold up better, with time, all opened wine turns to vinegar.
This is to quickly and tightly recork your open bottle and store it in a cool, dark place.
How effective this will be depends on how long the wine was open and the ratio of remaining wine to air. A bottle open for just long enough to pour a glass will have had less exposure than one left open on the table for hours.
Likewise, a bottle recorked with more than half its wine remaining will be more likely to hold up than one with just an inch or two left. To keep such a wine, pour what remains into a clean half-bottle, eliminating some or all of the headspace. It’s a cheap, no-tech solution.
If you’re tempted by tech, however, plug-and-pump systems (manual or electric) go further, drawing air out of a bottle, usually through a self-sealing rubber stopper. Though manual models sell for about $10—I use the Vacu Vin Wine Saver—I’ve never been convinced it’s that much better than my half-bottle solution.
Other systems address the problem by topping off partial bottles with inert gas, displacing the air inside. Just push the cork back in and move on. You don’t even need to uncork the wine if you have the Coravin One Wine System (starting at $200), which injects a bit of argon gas through the cork. This approach—not to mention its cost—is extravagant for home use.
Preserving leftover wine may be fine, but I worry it can have a counterproductive effect, too. In the end, wine isn’t a thing so much as an event. Opening a bottle sets wine on a path of change, growth and evolution. To have a bit left over is to have a glimpse into its future; in a sense, to share that future.