Oxygen plays a very important role in the winemaking process. The winemaker is always trying to limit the amount of oxygen, but it truly is a balancing act. Too little oxygen, the wine is reductive and you get that onion smell. It can be really potent and typically green onions or green scallions is not a positive aromatic.
On the opposite side of the spectrum there can also be too much oxygen. When this happens the wine is called oxidative. As opposed to the onion smell, you get that nuttiness. The classic example is an Oloroso sherry. In the case of sherry, it is meant to be oxidative. The winemaker purposely wants the flor – the layer of microorganisms.
There are certain varietals, such as Riesling, that are prone to oxidation and there are certain varieties of wine that we want to be slightly oxidative. In the end, it all comes down to the winemaker’s vision for the wine. This is the balancing act of oxygen and wine. We produce the wine so that once it is in bottle, it’s ready for it to be the way we want you to enjoy it. But then you go ahead and you unscrew or uncork it. Once this happens the oxygen comes rushing into the bottle and excessive oxidation of the wine begins.
Depending on how much oxygen was in that wine to start off with it becomes like a race when the bottle is opened. As the oxygen comes in all of a sudden, those aromatics and those flavors start to open up, they loosen up a bit. And that’s why we swirl our glasses; to give little micro oxygenation.
It’s the micro vs. macro that matters. During the winemaking process, we don’t want macro. At some point, the oxygen’s impact on the aromatics begins to become negative. And that’s the problem. If you open a bottle sometimes it might smell a little sulfur but it really is not a fault in the wine, it just needs to open up. It needs to breathe, because it’s been bottled up for such a long time.
Think of yourself if you were stuck in a closet for a long period of time, you will start to close yourself off. Same thing with the wine, it’s going to close. So those sulfur or dusty odors can diminish as soon as you open it, and you swirl the wine. Tannins can have a similar effect. Without oxygen, they may be overpowering and sometimes, swirling may not be able to add enough oxygen to soften them. This is where decanters come to the rescue.
When decanting, we want to keep in mind that leaving the wine open to the air too long can make us miss that ideal aromatic opportunity. Also keep in mind there are certain wines that you may not want to decant like significantly older red wines. You might want to be a little worrisome about decanting, because as they’re that old, they get very gentle, they get very fragile. By pouring it into a decanter, you might damage the fragile compounds.
Fortunately, there is no set rule for what a decanter has to be. They come in a wide variety of shapes, sizes, and price ranges. If you want to purchase one of the fancy ones, enjoy! But you don’t need to buy a decanter, you can use any vase. (or take a trip to the dollar store) One of they many you probably have hanging around the house from flowers. Just remember, to pour the wine gently into the decanter, it is not advisable to “dump” the wine – but of course that would be another way to add to the macro oxygenation of the wine. Typical reds can really vary between 30 minutes and two hours depending on how much.
Sometimes you don’t have the patience to sit and let the decanter do its job, or you forgot to open the bottle early enough in the day for proper decanting. This is where aerators come to the rescue. Some aerators introduce air as the wine travels through the device, while others disperse the wine by flowing it though various spouts.