What makes wine age longer

There are 4 major elements that give wine the ability to age:
the tannins, the PH, the alcohol and the sulfites.
Tannins are molecular antioxidants that are present in the majority of trees and fruits. In grapes there is a higher concentration of them in the stems, seeds and the skins, commonly called the "dregs." The tannins are transferred into the wine during the maceration, when the wine is in contact with the dregs.
Acidity also plays a big role in the aging process. An alkaline wine with a high PH level, say for instance, a buttery California Chardonnay, will have a lower capacity for ageing than acidic wines with a lower PH. The acidity also acts as an antioxidant.
The alcohol in wine has a familiar task, acting as an antiseptic and a preservative, just as it does in medical science. This helps to keep the wine safe and uninfected by harmful bacterias.
The sulfites are the final antioxidants in wine. They are present in nature, and are sometimes added in small amounts, usually to stabilize a wine.
The main component in preserving the life of a wine is the same as it would be in any living thing - electricity. Tannins, like all molecules, retain an electric charge. By utilizing that charge, the tannins capture oxygen molecules in the wine, creating a sort of protective shield. The tannins can also be transferred into the wine from the barrels in which the wine is fermented. In this case, the wood will give an additional modicum of electric charge to the wine, enhancing its antioxidant properties. Connected to the tannins are flavonoids called anthocyanins and leucoanthocyanins (more antioxidants), which are also responsible for the wine's color; the first results in a purple color, and the second is white.
It is also very interesting to see how the barrel plays a role in the color of a wood-aged red wine. The barrel, as previously stated, will transfer significant electric charges to the wine that strengthen the anthocyanins, and make them show an almost blue color.
These excess charges, in addition to strengthening the wine in a general sense, also help to shorten the chemical chain of the wine's tannins. If the chain were to get too long and heavy (a danger to which it is highly susceptible, especially after long maceration on the skin) it makes the tannins sink to the bottom of the barrel, where they are discharged with the dregs, robbing the wine of its ageing potential. This is why simply having wine in contact with the grape skins doesn't guarantee a higher content of tannins unless they are refined and recharged by wood.
So - a wine with the right amount of sulfites (too much will give a rotten egg flavor to the wine), a good amount of charged tannins with wood to balance out their chemical chains, and a lower PH level will allow the bottle to live for several decades.
Here's an example for you to try, to experience the influence of the PH levels in a wine; see how a barriqued Chardonnay tastes different when it comes from California or Sicily. Then compare it to a Chablis or a Chardonnay from Trentino Alto Adige. The first will have a higher PH level, resulting in fat, buttery, soft, round texture and a shorter life, where the Chablis, which will retain a very low PH level will have sharp, crispy, fresh texture, and the possibility to age for 30 40 years.
Last but not least, the sulfites, naturally produced during the fermentation of a wine, are another powerful antioxidant. If used in moderation, they can only expand the wine's life. But if overused, they can and will "kill" the wine, again with the "rotten eggs" flavor.
Regarding the sulfites - I remember a very inspirational story regarding Stanko Radikon, a winemaker from Friuli-Venezia Giulia.
I had the pleasure of meeting the Radikon family, and had dinner at il Buco with different vintages of the Ribolla Gialla, Oslavje and Oslavje Riserva. They also brought a bottle of Oslavje vinified with added sulfites, and one from the same vintage that was sulfite-free (starting with the 2002 vintage all his production is without added sulfite)
The one without added sulfites was more open and ready than the other. The bouquet was firmer, to say the least. This makes sense, because technically, the wine with added sulfites was 5 years behind the one without. Interesting, eh?
In closing, I would like to apologize for my prolonged silence - it took quite a while to try to simplify a very complex chemical process from a slough of Italian words that are not translatable.
Stay tuned for the second part of the aging experience.
Buona Bevuta a Tutti