Why does wine age in the bottle?

[mbanu]

If this has already been covered somewhere, I apologize.

So why exactly does wine age in the bottle? Is it mostly chemical reactions between the wine's various components? And why does this supposedly only happen with wine and not with spirits? For instance, I've read things which mention how tannins precipitate in the bottle over time, leading to a more mellow wine. But most spirits contain tannins as well... does this not happen with spirits, or are the people who say spirits don't change in the bottle incorrect? What other sort of chemical changes does wine go through in the bottle? Is the difference because spirits are generally sealed with screwcaps, while wine is mostly sealed with corks? Does it have to do with the alcohol content?

Any help would be greatly appreciated.

[jsolomon]

The main reason is that there are a lot of chemical components present in wine that are removed in the distillation process to make spirits. Almost, if not all, of the enzymes and large chemically reactive species in wine are not present in spirits directly because of distillation.

All of that cellular machinery continues to do chemistry (even if it's "unintended" chemistry) long after the cells are dead. Additionally, as that cellular machinery ages and falls apart, it still has the possibility to do chemistry, which continues to happen. Changes in pH cause changes in enzyme activity. So do changes in other molecule concentrations.

However, since spirits are simpler, and lack those large molecules, it doesn't change nearly as much with aging.

[Brad Ballinger]

The "aging" is a much different process with fermented beverages versus distilled beverages . Wine still has components that will change or develop chemically over time, even in the vacuum of a bottle. Bottle closures (corks v. screwcaps) play a role to an extent in that the cork ever so gradually allows oxygen into the bottle over a long, long time. Other factors that contribute to a wine's evolution (or deterioration) in the bottle include vibration, temperature, and humidity -- and I'm not aware of these having much of an effect on distilled spirits (though possibly temperature does, but I truly don't know).

Wine is still a "living" product in the bottle. It is perishable.

[jayt90]

The "aging" is a much different process with fermented beverages versus distilled beverages .  Wine still has components that will change or develop chemically over time, even in the vacuum of a bottle.  Bottle closures (corks v. screwcaps) play a role to an extent in that the cork ever so gradually allows oxygen into the bottle over a long, long time.  Other factors that contribute to a wine's evolution (or deterioration) in the bottle include vibration, temperature, and humidity -- and I'm not aware of these having much of an effect on distilled spirits (though possibly temperature does, but I truly don't know).

Wine is still a "living" product in the bottle.  It is perishable.

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Brad, what is the effect of humidity in a cellar? I can understand the other factors, but I don't know how humid, moderate, or dry air would get through the cork differently.

Also, as we enter a screw cap era, the amount of aeration permitted during vat, barrel, and bottling stages would seem to take on a greater role, not to mention air or gas allowed into the neck when the cap is fixed.

[Brad Ballinger]

Brad, what is the effect of humidity in a cellar? I can understand the other factors, but I don't know how humid, moderate, or dry air would get through the cork differently.

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Humid air helps to keep the cork from drying out.

[Mallet]

Although I am far from an expert, I have noticed that some spirits do seem to "age" in the bottle after it is opened. Fine spirits especially tend to mellow out and become more complex after the bottle has been opened and allowed to sit for a while, but will degrade if left around to long. Has anybody else noticed this?

[Really Nice!]

It's oxidizing. There are two forms of aging: biological where the beverage is closed and allowed to change the elements within it over a long period of time; and physiochemical, which is putting the beverage in direct contact with air and its oxidizing effects.

Some wines you want oxidation, such as Madeira, Marsala, or Sherry (or it doesn't hurt as much). With just about all other wines, however, oxidation will diminish the overall effect after being opened two or three days.

With distilled spirits oxidation takes much longer. If left opened too long it tends to turn stale.

[Brad Ballinger]

It's oxidizing. There are two forms of aging: biological where the beverage is closed and allowed to change the elements within it over a long period of time; and physiochemical, which is putting the beverage in direct contact with air and its oxidizing effects.

Some wines you want oxidation, such as Madeira, Marsala, or Sherry (or it doesn't hurt as much). With just about all other wines, however, oxidation will diminish the overall effect after being opened two or three days.

With distilled spirits oxidation takes much longer. If left opened too long it tends to turn stale.

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Actually, with wines where you want oxidation, most of that takes place prior to bottling, and mbanu's question was about the beverage in the bottle. Many distilled spirits are also oxidized prior to bottling -- otherwise there wouldn't be a big deal about 12 year old scotch.

[Really Nice!]

Actually, with wines where you want oxidation, most of that takes place prior to bottling...

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Ohhh details, details, details...

Excellent clarification, thanks!