How to Keep “Leftover” Wine
What is “leftover” wine? For some, it is hard to imagine such a thing. The best case scenario is not to leave any wine in a bottle. But, if you sometimes find wine left in the bottle(s) after dinner or at evening’s end, what can be done about it?
My preferred “best practice” is as follows: immediately after opening a bottle, transfer one-half of the wine into a smaller container - a half-bottle from a previously enjoyed wine, or a well-washed 12 ounce plastic beverage bottle will do. The smaller container needs a tight-fitting closure - a cork, stopper or snug-fitting screwcap. My favorite is a wine half-bottle with a screwcap.
How and why does this best practice actually work? There are basically four 6 ounce glasses of wine in a 750 mL bottle, so immediately pouring half of the freshly opened wine to completely fill a smaller container will leave two nice glasses of wine ready to serve. Sealing the smaller container will minimize air (oxygen) contact that will degrade the wine. Refrigerating the sealed, smaller container reduces the rate of oxidative degradation. This technique has provided drinkable wine even after 3-4 days. All one needs to do is warm it up a bit and enjoy when ready.
Leftover wine in the original bottle will begin to oxidize immediately, and can result in significant degradation in aroma & flavor overnight. Refrigerating the partially filled bottle will help, but air is still in there. The best results expected from this practice would be one, maybe two days of drinkability.
An effective method to preserve leftover wine for several days is displacing air with an inert gas, nitrogen or argon. Argon is great because it is more dense than air and displaces air from the bottle. In order to use a compressed gas cylinder safely, a pressure regulator is needed, adding even more expense. Or, one can find several gassing systems for home or commercial use on the internet or in commonly distributed wine catalogs.
Removing air using self-sealing stoppers and a small hand pump to pull a vacuum is a widely used technique. The advantage is less air left to oxidize the wine. The disadvantage is that when a vacuum is pulled, a portion of the wine’s volatile aroma and flavor components are also removed. Since what you taste in a wine is 80+% related to what you smell, removing these important volatile compounds appears a less than favorable approach.
However you decide to deal with this issue, here are two key things to remember.
1. Air contains oxygen and in contact with wine will cause oxidative degradation over time.
2. Refrigeration slows oxidative degradation and will increase the drinkability window.