How long does an unopened bottle of wine keep?

Under the European labelling rules, wine with 10 percent alcohol by volume or more is exempt from the best-before date. So no date belongs on it, and nothing is missing.

Annex X, point 1(d) of Regulation (EU) No 1169/2011 lists two exceptions that coincide here. The first applies to wines, liqueur wines, sparkling wines, aromatised wines and similar products made from fruit other than grapes. The second applies to all drinks with 10 percent alcohol by volume or more. If the alcohol content falls below 10 percent, for example with a light or dealcoholised wine, the Dutch government says a best-before date must appear on the label.

What must be on it is laid down in the wine labelling rules: the wine category, the origin, the actual alcoholic strength by volume, the bottle contents, the bottler, the batch number and the allergen information. For sparkling wine, the sugar content is added. The year on the label is the harvest year, not a best-before date.

An ordinary white wine keeps its quality, if stored well, for about three years after bottling, an ordinary red wine for about three to ten years. Those are orders of magnitude, not end dates.

The enology department of Purdue University gives those periods as a general guideline and immediately adds that the spread is large: some wines are meant to be drunk within a year, others last for decades. A bottle rarely becomes undrinkable after that period. It becomes flatter: the fruit fades, the colour becomes duller and white wine turns towards golden brown.

In de winkel aan de Brink 2 in Bathmen staan 1.082 wijnen: 419 rood, 309 wit, 86 mousserend, 42 champagne, 39 dessertwijn en 38 rosé. Alleen al bij de stevige rode wijnen gaat het om 142 flessen van 84 merken uit 12 landen, waarvan 47 uit Frankrijk, 37 uit Italië, 15 uit Spanje en 14 uit Chili. Wij verkopen alleen aan achttien jaar en ouder, NIX18.

Temperature weighs the heaviest. Purdue University advises 10 to 16 degrees for long-term storage, with a fluctuation of at most 1 to 1.5 degrees.

Above 16 degrees maturation speeds up and shelf life shortens, especially with white wine. Above 24 degrees practically every wine ages strongly and undesirably, and 30 degrees or more should never occur, not even briefly. The Australian Wine Research Institute arrives at the same conclusion: over a longer period above 25 degrees quality suffers, and in a trial from 1986 wine showed off-flavours after twelve months at 30 degrees. Too cold is not good either. Below 10 degrees the aroma develops less, around 0 degrees tartrate crystals can form within about an hour, and at 5 degrees below zero a wine with 14 percent alcohol or less can freeze and break the bottle.

Light is the second factor. In trials, wines in clear glass developed an off, lightstruck aroma after only about three and a half hours of fluorescent light; in green glass it took much longer, and direct sunlight is more damaging than fluorescent light. A dark cupboard is therefore better than a sunny windowsill. Less is known about vibration than is often thought: the Australian Wine Research Institute searched for literature demonstrating damage from vibration and found none. Also keep the temperature stable, because moving a bottle from very cold to warm causes condensation, and condensation can cause mould on the label and cork.

Look at the fill level, at leakage along the neck, at a cork that has been pushed up and at the color. These are the visible traces of heat damage.

Heat expands the contents. According to the Australian Wine Research Institute, this can cause wine to leak past the cork or the cork to push up. Such a bottle looks bad, and that is a reason not to give it as a gift, but it does not automatically mean the wine underneath has suffered. A clearly lowered fill level in a bottle that is too young for that is, however, a serious signal.

Color says the rest. A white wine that has turned deep golden-brown while the style does not call for it, and a red wine with a brown rim, have largely lost their fruit. Crystals on the bottom or under the cork are not spoilage: that is tartrate, caused by cold. If a bottle smells musty or of a wet cardboard box, that is cork taint, a fault of the closure and not of age.

Yes. A screw cap lets the least oxygen through and keeps bottles of the same wine more uniform with one another, whereas natural cork differs strongly from piece to piece.

In the closure trial that the Australian Wine Research Institute started in 1999, fourteen closures were applied to the same semillon. The screw caps held on to the sulphur dioxide best, preserved the fruit longest and limited the discolouration to yellow and brown. Next came the pressed corks, then the natural corks. The best natural corks achieve the same result as a screw cap, but the spread between individual corks is much greater, and that is precisely why two bottles under screw cap resemble each other more than two bottles under cork.

For storing at home, a practical difference follows from that. A bottle with natural cork you lay on its side or upside down, so the cork stays wet and less oxygen gets in; a bottle with a screw cap can simply stand upright. Cork taint belongs to cork: the institute cites 1.3 percent in a large international competition, against 5.5 percent in 1994 and 5 to 8 percent in the years 2001 to 2003.