Wine Reviewers

History

Decanters have an interesting history, and they have played a role in one fashion or another in the process of the serving wine. Ancient Rome was the place which pioneered the usage of glass as a material, and after the fall of the Roman Empire, glass production was hardly in existence, causing the majority of decanters to be made of semi-precious metals such as bronze, and precious metals such as, silver, gold, or even earthenware (made from clays etc.). Later, the Venetians reintroduced glass decanters during the Renaissance period in which time the style of a long slender neck that opens to a wide body became ever more popular, increasing the exposed surface area of the wine, which in turn increased oxidation.

Decanting Process

Liquid from another vessel, usually significant larger, is poured into the decanter in order to separate a volume of liquid, containing sediment, from a larger volume of “clear” liquid. In the process, the sediment is left behind in the original vessel, and the clear liquid is transferred to the decanter. Ultimately the first point of decanting is to dismiss the sediment.Decanting wine can also aerate the wine. This controversial process may, either benefit the wine by smoothing some of the harsher aspects of the wine (like tannins or mercaptans) or it may be detrimental to the wine by causing too much oxidation and the potential to lose some of its aromatic properties.

Aeration

On the subject of aeration, wikipedia has this wonderful bit:

Another purpose that decanting can serve is to aerate the wine or to allow it “to breathe”. In this regard the decanter is meant to mimic the effects of swirling the wine glass to stimulate the movement of molecules in the wine to trigger the release of more aroma compounds. The effectiveness of decanting is a topic of debate with some wine experts, like oenologist Émile Peynaud, claiming that the prolonged exposure to oxygen actually diffuses and dissipates more aroma compounds than it stimulates in contrast to the effects of the smaller scale exposure and immediate release that swirling the wine in a drinker’s glass has. Still main wine writers, such as author Katherine McNeil in book The Wine Bible, advocate the use of decanting for the benefit of aeration, especially with very tannic wines like Barolo, Bordeaux, Cabernet Sauvignon, Port, and Rhône wines while noting that decanting could be harmful for more delicate wines like Chianti, Pinot noir and Rioja wine. However, the process of decanting, over a period a few hours, doesn’t have the effect of softening tannins. The softening of tannins occur during the winemaking and oak when tannins go through a process of polymerization that can last days or weeks. Decanting does have the effect of altering the perception of sulfites and other chemical compounds in the wine through oxidation which can give some drinkers the perception of softer tannins.    

Either way, decanters are a must-have in a wine-enthusiasts arsenal.