Answer: What do you mean you didn’t finish it?? Just kidding (sort of). The main obstacle with keeping a wine that’s been opened is that by unscrewing that cap or popping that cork you have introduced wine’s initial friend but inevitable enemy: oxygen. Allowing a wine to “breathe” is definitely beneficial in the short term, but eventually it can lead to wine turning undrinkable. After all, wine is an organic product, so just like when you open any other type of food, it will sooner or later spoil. Even if it’s still safe to drink a wine when it’s gone vinegary, you probably won’t want to.
Fun Fact: Age often matters- older wines are fragile and tend to lose their pizzazz faster than young wines when exposed to air. This is why decanting or aerating pourers can actually do more harm than good when it comes to old bottles!
Fear not, there are some short-term solutions (with emphasis on “short) to keeping a bottle after you’ve opened it:
Option 1: wine stoppers and/or the cork (pictured above). Whether you choose a handcrafted Murano glass stopper or the bottle’s original cork, this is the easiest, cheapest, and surprisngly effective way to save a bottle. But remember, no bottle is ever truly half empty: where there isn’t wine inside there’s air! That means you had better finish it within a few days as it changes or risk finding it too dull or sour for your taste.
Option 2: wine vacuum pumps (see picture below). Vacuum pumps are a cheap way to save a bottle for a day or two. They work by having a stopper and hand pump that pulls all of the air out of the bottle, preventing as much air exposure as possible. They typically cost between $10-$15. There is however strong disagreement about their efficacy (i.e. if they actually maintain the vacuum) in the wine community. And also some suggestion that they might actually harm a wine’s aromas.
Option 3: Gas systems. These remove air inside the bottle by replacing it with an inert gas (typically argon or nitrogen). Some of these even work by going in through the cork – meaning never even having to remove the cork in the first place! These are extremely effective but also extremely expensive, as it requires buying replacement gas. This is a better option for beverage professionals like wine reps who regularly have bottles with them that are half-empty (or half-full for optimists).
Option 4: Bottle-switching. Keep some spare half-bottles (375-500ml capacity) around and transfer the remaining wine into this smaller bottle before putting on the stopper. This minimizes the amount of oxygen left in the bottle to interact with the wine.
Some other things to keep in mind when you are trying to hang on to a bottle, open or not, are temperature and light. It’s better to keep a bottle somewhere cool (like your fridge) and away from sunlight or bright/hot lights, as heat speeds up the spoiling process. Also, places that get very warm, like kitchens, are not ideal for keeping wines in general – opened or closed. Not only does the heat speed up spoilage, but the temperature fluctuations in kitchens can be detrimental to unopened bottles’ corks by causing them to constantly expand and shrink – potentially leading to corks failing.
Keeping sparkling wines like Prosecco after they’ve been opened is a little trickier – bubbly wines lose their beloved sparkle fast. There are special stoppers meant to keep in the carbonation which are both effective and inexpensive and will help save leftover sparkling wine (short-term). In case you’ve heard the old trick about sticking a spoon in the bottle, there is no evidence to support the theory that putting something metal, like a spoon, in the bottle will help it keep its bubbles any longer.
Fortified wines (e.g. Sherry, Port, Madeira, Marsala) are wines that are actually built to last longer in the first place, which means that an opened bottle can last much longer than a non-fortified wine (e.g. Chianti, Pinot Grigio, etc). These can last for months with only their original cork and having a safe spot in the fridge. Also, fortified wines used for cooking (e.g. Marsala) are the only wines that are OK to have sitting on the kitchen counter for any period of time.