One of the most confusing things about wine is knowing whether, how well and how long a particular bottle will age.
Anyone who has drunk a well-aged wine at its peak will know that the pleasure can be sublime. However, we have all probably kept an expensive wine for a long time - to find that it is over the hill when that special occasion came.
The first thing to realise is that not all wines are made to age gracefully. In today's world of instant gratification, many wines, even quite expensive ones, are made to be enjoyed within a couple of years of bottling.
In order to age, wines need to have certain preserving attributes. These are acidity, sugar, alcohol and tannin. Not all four are required but a wine that lacks them will ‘fall over’ with time. The wine also has to have sufficient concentration of flavours that will be released in the future.
Acidity is important mainly for white wines, including sparkling ones. Good examples are Champagne, Alsace, Chablis and white Bordeaux. Well-made examples can age for 5-10 years.
Sugar is the key preservative in the sweet wines of Sauternes, Montbazillac, the Loire and certain areas of South-West France. They age for decades. High alcohol makes sweet fortified wines age slowly for many decades. Banyuls, Rivesaltes and Maury are the main French examples.
Finally, tannin is the most important, interesting and frustrating ageing component of red wines. Tannin is a preserving agent which alters over time. It comes mainly from the skins of red grapes but also from oak barrels. It starts out as short molecules, which translate as an astringent feeling or drying in the mouth. Over years in the bottle the tannins join up to form longer molecules, which feel more velvety and less "grippy". Eventually they become so large that they fall out of solution and form a sediment. All through this process they release other volatile phenols into the wine - which we perceive as the bouquet. Often they resemble dried flowers, sandalwood, furniture polish or eastern spices.
Often, wines which rely on acidity and/or tannin to age will appear unpleasant when they are young. This is the cause of the misconception among anti-snobs that expensive wines are not really that good. A young Pauillac, Vougeot or Cote-Rotie can be pretty off-putting.
In general, the best wines for ageing come from the classic regions of France and are made in a traditional manner. However, some producers in the Languedoc-Roussillon and Beaujolais are making age-worthy wines too. It is quite difficult to predict exactly when a particular wine will be at its peak. It is a combination of vintage, winemaking choices and cellar conditions.
The ideal conditions for ageing wine are a dark room with a constant temperature of around 15 degrees. However, as long as the temperature does not changing much on a daily basis, a warmer room will not ruin wine. A spare bedroom, a garage or a broom cupboard will all work but there are also wine-fridges for homes that do not have much space. Wines with corks need to be laid down but screwcaps can be stored vertically.
My tips for building up a cellar are: Start gradually. Choose wines carefully. Take advice on producers and vintages. Buy several bottles of the same wine so you can chart its progress. Tag or organise wines with the year you plan to drink them. Do not focus too much on one region or vintage. Make sure you have plenty of other wines on hand for casual drinking, so you won't be tempted to dip into the cellar. And DO NOT let teenagers have a party in your house when you aren't there.
Jonathan Hesford has a Postgraduate Diploma in Viticulture and Oenology from Lincoln University, New Zealand and is the owner, vigneron and winemaker of Domaine Treloar in the Roussillon.