If you follow anything that I write about wine you will always see the caveat with each description, “decant this wine for _____ minutes before serving.” I try with many write-ups to explain why this is important but I feel it is important enough to devote an entire article on the subject.
It starts with a very simple premise about wine: oxygen builds flavor. When alcohol comes in contact with oxygen a series of complex chemical reactions occur and the result, in the most simple terms, is two-fold. The first is that compounds called esters are formed which are what create the aroma of wine. This same reaction occurs in nature, as fruit ripens the sugars begin to break down and also ferment, at very low levels. This is why strawberries that are past their prime often show a slightly alcoholic flavor. If allowed to continue to react to alcohol then acetic acid is formed, which is what creates vinegar. (A little known fact is that fruit flies are not attracted to ripe fruit but to the vinegar that forms as it decays.)
The other thing that happens when wine comes in contact with air is the structural change in the wine. This gets into some pretty heavy organic chemistry concepts but here is the gist of it. The color compounds in wine are called anthocyanins. These are the same antioxidants that are found in all dark fruit, from blueberries to blackberries. In wine they appear as long chemical chains. Think of them as a long line dance partners at an all girls school. Sure they don’t like dancing with themselves but without any men around it is the best option. Now comes oxygen, which in this case is a bus carrying dance partners from the all boys school down the street. Once the oxygen arrives then they basically don’t like dancing with each other and they start looking for better, more attractive partners. In the wine this is another compound called tannin. Tannin is the part of wine that makes the sides of your mouth dry. Well as the color compounds and the tannins dance, they form longer and longer chains, like a conga line. Eventually the conga line gets so long that it is bigger than the receptors on your tongue that perceives tannin, and the wine appears to be smoother.
This also happens to a bottle of wine that has been cellared for a length of time, usually a few years. A small amount of oxygen wiggles it’s way through the cells in the cork, or around the cork if the seal is bad, and works it’s way to the wine. This causes the same precipitation of color compounds in the bottle and they end up as sediment in the bottom, or on the sides, of the bottle. By decanting you will also remove these, which won’t hurt you but do leave a grainy residue in your mouth.
Now when I use the term “decanting” it means to actually pour the wine out of the bottle. Some people like to pull the cork and let the wine “breathe” but the surface area in the neck of the bottle is too small. You need to get the wine out of the bottle and expose as much of it as possible to air.
As for equipment, this does not mean you have to run out and buy a fancy, cut crystal decanter. Any glass or pottery piece will work, as long as it doesn’t absorb flavors. If the wine is young you don’t have to be delicate, just dump it in. Remember, the more oxygen you get into the wine, the faster the reaction. If the wine is older, say seven years or more, then you may want to take your time. A fine layer of sediment has probably formed on the sides or the bottom of the bottle and you want to try not to pour that out with the wine. It doesn’t hurt you if you drink it but it can be a bit gritty.
So when you read about how a wine needs little time in the decanter, take those directions to heart because it will greatly improve your enjoyment of that bottle.