Aging wine: A beginner's guide

In the average wine collector's cellar, you'll find more than a few aging, dusty bottles. Many red wines, with proper storage, actually get better with over time, hitting their optimum drinkability years after the vintage date. The flavours in a Cabernet Sauvignon will mellow and improve for ten to fifteen years, while Pinot Noir and Zinfandel will age well for five to ten years beyond the vintage date. White wines, on the other hand, should usually be consumed within two or three years.

So what's the difference, you ask? Why should you drink that white Chablis tonight, but save the red Bordeaux to celebrate the birth of your first grandchild? The answer is tannins. Red wines have them; most whites don't. Tannic compounds, found in the skins and seeds of grapes, lend an agreeable astringency (that "pucker" sensation) to wine. Tannins slow the oxidation process, allowing for greater aging potential.

Tannin extraction, crucial to making red wine, happens when the grape juice is fermented along with the tannin-rich skins (even the whole grape). For white wine, the juice is pressed out of the grape skins before fermentation, hence a lack of tannins and colour. The skins rise to the top of the juice and form a cap. The winemaker monitors tannin levels, manipulating the cap and removing it when the right amount of tannin has been achieved. Another process, called maceration (prolonged contact between juice and skins, occurring before or after fermentation) is also a source of tannins.

Tannins found in new wines can be bitter and occasionally render especially tannic young reds undrinkable. If you imagine the taste of over-steeped tea (another high-tannin beverage) and you'll get the idea.

Aging begins early, during maceration and fermentation. The tannic compounds join up with each other, as well as with the pigment molecules, to form long polymers. In the vat, the wine is exposed to a lot of oxygen, so initially, this process happens quite quickly. In the bottle, the tannins absorb any oxygen in the wine and headspace (that is, the air in the bottleneck). Once the oxygen is gone, the process becomes anaerobic and slows considerably. Varietal compounds interact with each other and with any oak compounds gained during fermentation and barrel aging. Polymers continue to form, eventually settling out of the wine and turning the tannins from bitter to silky. The colour of the wine changes from purple or ruby to brick-red, and the flavours and aromas deepen in complexity.

All the tannins in the world won't make the perfect wine if you if you plunk it down next to the radiator for the next five years. You've got to store it properly. The ideal climate for wine is cool, damp, and dark - like a cave or, failing that, a basement. Warm temperatures will make wine age faster. Store bottles on their sides at a stable 55-65F to slow this process. The more slowly wine ages, the more complex the flavours can become. Stable temperature is important as variations cause wine to expand and contract, pushing and pulling the cork and allowing more oxygen to enter the bottle. This could spoil your investment Bordeaux! Your best bets for aging potential are large format bottles (i.e. magnums or greater), where the oxygen is consumed by a greater amount of liquid, making the aging process even slower.

To choose a wine that will age well, educate yourself. Speak to your local wine merchant or consult a specialized wine journal to find out which wines have potential, then buy a case or two. A wine made with Cabernet Sauvignon or Pinot Noir grapes is a good place to start. Take care to store the wine properly and sample a bottle every once in a while. Make tasting notes so you can see how the astringency, aromas and flavours of the wine develop and change over the coming years.