Wine aeration and decanting are two important steps in wine enjoyment, and unfortunately, the terms are sometimes confused as being interchangeable.
Aeration is the exposure of wine to air. Aeration occurs throughout the winemaking process and is controlled from fermentation to bottling.
Decanting is exactly what it sounds like: the process of transferring wine from its bottle to another container. Decanting is most often employed to separate the sediment of an aged wine before drinking it. Many contend aeration is a crucial step in the decanting process, promoting the wine’s developing aromas, flavors and finish.
Professor Emile Peynaud (1912-2004), world-renowned scientist, taster and teacher, argued that oxygen coming in contact with a sound wine does more harm than good. According to his theory, the longer the wine was aerated during decanting the more diffuse its aromas and less marked its sensory attributes. He advised to only decant wines with sediment and only just before serving. This is because the moment wine is fully exposed to air as it is poured, some of its sensory impressions may be lost and pouring just prior to serving gives the taster maximum control.
This theory is easily proven in fragile, fully developed 20-to 30-year-old wines. Many of these wines are so delicate they can only withstand minutes in a glass before giving in to the negative impact of aeration, which is oxidation.
However, there are many wines where aeration during pouring or decanting is desired, such as youthful wines with high tannins or traditionally robust full-bodied wines such as a Barolo. Some wines are so overpowering and tannic when young that an hour or so sitting in a decanter or even a few added swirls in your glass will offer tremendous benefits.
If you have a bottle with sediment, here are instructions for decanting:
Start by placing the bottle upright for at least 24 hours to allow sediment from the sides of the bottle to dislodge. Open the bottle as you would any other wine, being careful to not disturb sediment that has settled on the bottom. Slowly tip the bottle on its side while slowly pouring its contents into the decanter. To see the sediment as it flows, place a candle under the neck of the bottle; it will be a thin, grainy streak at the beginning of the pouring but will become thicker and sludgy at the end. If time is an issue, filter the wine through cheesecloth or, as a last resort, a paper coffee filter.