How Long Does Unopened Wine Last? Heat and Light

How long does unopened wine last? Heat and light decide, and both work faster than the people stacking cases in a spare room expect. The Australian Wine Research Institute's review of the storage literature supplies the numbers. Marais found faulty flavours and decreasing overall quality after 12 months of storage at 30°C. Ough found that temperatures in excess of 40°C induce visual and sensory changes in a matter of days, and set the working ceiling at 25°C over long periods, 40°C over short ones. Light is quicker still: Dozon and Noble measured a statistically significant lightstruck flavour in white wines after 3.3 hours under fluorescent lamps in clear glass. So how long does unopened wine last has two answers. Dark, steady and 15 to 20°C, and a wine built for cellaring does what it was made to do. Warm it or light it, and the clock runs in months or hours rather than years.

Does unopened wine go bad?

Yes, and heat is the quickest route there. Excessive storage temperatures have a marked effect on the shelf life of bottled wine, and the AWRI's summary of the evidence is specific about where the thresholds sit.

Marais reports the development of faulty flavours and decreasing overall quality after 12 months of storage at 30°C. Ough found that temperatures in excess of 40°C induce visual and sensory changes in only a matter of days. Ough's later guidance is the line to work to in practice: any storage place where the temperature exceeds 25°C for long periods and 40°C for short periods can affect wine quality. That threshold, not room temperature, is the number to design storage around, which is why wine storage temperature is the first thing to fix and hot weather storage the second.

Heat also does damage you can see before you taste anything. Wine expands, and the AWRI notes that leakage of wine or movement of cork stoppers can follow exposure to temperatures significantly greater than ambient. That physical damage does not necessarily imply the quality of the wine has been affected, but it affects the appearance, and therefore the marketability, of the bottle. If you ever intend to sell, that distinction is the gap between a clean lot and a discounted one.

Proving heat damage afterwards is harder than it sounds. The AWRI's position is that physical, chemical and sensory tests are required to establish whether damage has occurred, judged against bottles of the same wine that were never exposed. Finding those control bottles is not always possible.

How fast does light damage a bottle?

Hours, if the glass is clear. Maujean and Seguin found that lightstruck flavour, the goûts de lumière, is due to the formation of volatile sulfur compounds believed to derive from the sulfur containing amino acids methionine and cysteine. Riboflavin, vitamin B2, is the trigger. It sits at low levels in musts and wines, and it undergoes photo-activation and subsequent reduction when exposed to light at wavelengths of 370 nm and 440 nm.

Dozon and Noble put exposure figures on it. Still and sparkling white wines in green glass reached a statistically significant lightstruck flavour after 31.1 hours and 18 hours under fluorescent lamps. The same wines in clear glass got there in 3.3 hours and 3.4 hours. Descriptive analysis of the affected wines found a decrease in citrus aromas and an increase in cooked cabbage, corn, wet wool or wet dog, and soy or marmite.

Two things stop that being a reason to panic about the strip light in your storage room. The trial bottles sat 35 cm from two 40 watt fluorescent lamps, and illuminance decreases with the square of the distance from the source, so bottles further back take far less. Daylight is the real problem. A 36 W fluorescent lamp at an illuminance of 400 lux provides roughly 14 mW/m2 of UV-A radiation, while UV-A in full sunlight runs to 60,000 mW/m2. Direct sunlight therefore delivers 4,286 times the UV-A of a fluorescent tube, and the AWRI expects sunlight exposure, as in a retail window display, to be more deleterious than electric lighting. Keep the case out of the sun before you worry about light in wine storage generally.

Why do the bottles at the top of a stack go hazy?

Copper, brought out by light. The AWRI has investigated cases of haze in white wine where bottles stored on the uppermost layer of bins developed a haze while the bottles underneath showed no precipitation at all. In those cases the haze was invariably found to be attributable to copper instability.

The threshold is published. White wines containing a copper concentration greater than approximately 0.5 mg/L are likely to be susceptible to copper haze, and above that arbitrary limit the AWRI is blunt: protection from exposure to light will only delay the inevitable. Glass colour helps without solving it. Rankine states that amber glass is most effective in excluding wavelengths below about 450 nm, though the AWRI concedes the colour chosen is dictated more by marketing concerns than technical ones. Of the haze investigations the Institute has run in recent years, a disproportionately high number involved wines in clear glass bottles.

Some wines start further along that road. During the tirage process used to make méthode champenoise wines, autolysis liberates amino acids from yeast cells, which can raise the concentration of sulfur containing amino acids above the level in the base wine. Same lamp, more exposed wine.

How long does unopened wine last, style by style?

It depends on what the wine was built for, and most wine was not built for waiting. We note that the vast majority of wines are produced to be drunk young and fresh, with Beaujolais nouveau as the extreme case: a style made to be consumed within months of its bottling.

Bordeaux splits along the same line. Bordeaux AOC and Bordeaux Supérieur AOC together accounted for 55% of all Bordeaux wines sold in the world in 2010, and the Bordeaux AOC wines tend to be fruity, with minimal influence of oak, produced in a style meant to be drunk young. Bordeaux Supérieur comes from the same area under stricter controls, including lower yields, and is often aged in oak. Move up the pyramid and the intent inverts. The Right Bank wines around Libourne, Saint-Émilion and Pomerol among them, often have great fruit concentration, softer tannins and are long-lived. Left Bank Graves and Médoc wines are described as "concentrated, tannic, long-lived and most of them meant to be cellared before drinking", and the five First Growths sit there. The Bordeaux producer map shows how the two banks divide.

That longevity is also why these bottles fill salerooms. Bordeaux wines tend to be the most common wines at wine auctions because of the combination of longevity, fairly large production and an established reputation. Where those bottles are trading now sits in the fine wine market index.

Does the vintage on the label tell you how long the wine will last?

Less than the chart implies. The importance assigned to vintage is both varied and disputed. It counts for most in regions at the colder climatic limits of wine production, where some seasons are warmer and produce riper grapes, while a poor growing season leaves juice higher in acid and lower in sugar. In many New World regions the growing seasons are far more uniform, helped by the systematic and controlled use of irrigation, so the year on the label carries less information.

Roman Weil, professor at the University of Chicago and co-chairman of the Oenonomy Society of the US, tested the hypothesis that experienced wine drinkers "cannot distinguish in blind tastings the wine of years rated high from those of years rated low". He used wines ranging from four to 17 years beyond their vintage with 240 wine drinkers. They could not distinguish good vintages from bad, except for Bordeaux. Where they could, the match between their individual assessments and the charts' rankings was little better than tossing a coin. Replicated with wine experts, including French wine academics, the results were again the same as chance.

Frank J. Prial of the New York Times declared the vintage chart dead, writing that "winemakers of the world have rendered the vintage chart obsolete". James Laube of Wine Spectator has asserted that "even an average vintage can yield some grand wines". Weil does not consider the chart useless: he suggests using one to find good buys, since wine made in years considered worse than average may be priced far below its actual quality. The Bordelais put it more plainly. Their saying is "The best vintage is the vintage we have to sell".

What are the ideal storage conditions for bottled wine?

Cool, dark, steady, and with the cork wet. Amon and Simpson recommend that bottled wine be stored with the cork in contact with the wine in a cool, dry location at 15 to 20°C. The AWRI recommends storage under insulated or temperature-controlled conditions that minimise fluctuations in both temperature and humidity, and suggests miniature temperature logging devices recording at regular intervals as a way to monitor those fluctuations during storage and transport. Log the transport leg as well as the store: a case that crossed a summer tarmac has a history the label will not tell you.

The kitchen fridge is not the answer for the long term. The AWRI reports the belief that prolonged storage of wine in a refrigerator could adversely affect quality, on the argument that vibrations from the compressor are detrimental, but the Institute has been unable to find any literature on the subject. Treat that as unresolved rather than proven, and read vibration in wine storage before you build a rack on top of a compressor.

Condition	Effect on the wine
12 months at 30°C	Faulty flavours, decreasing overall quality
Above 40°C	Visual and sensory changes in a matter of days
Above 25°C for long periods, 40°C for short	Can affect wine quality
Fluorescent light, clear glass	Statistically significant lightstruck flavour in 3.3 to 3.4 hours
Fluorescent light, green glass	Same effect takes 18 to 31.1 hours
Light exposure, sensory result	Less citrus aroma, more cooked cabbage, corn, wet wool, soy or marmite
Copper above 0.5 mg/L plus light	Copper haze in white wine, light protection only delays it
Refrigerator vibration	Believed detrimental, no supporting literature found
Heat spike causing leakage or cork movement	Hits appearance and marketability, not necessarily quality
Cork in contact with wine, cool and dry, 15 to 20°C	The recommended condition

When should you stop holding and start drinking?

When the wine reaches the top of its window, not when the storage fails. Storage sets the ceiling on how long an unopened bottle lasts. A drinking window tells you where inside that ceiling a given bottle sits, and how long you can store wine covers the practical limits by style. Get the conditions right first: the full storage guide is the checklist.

Stop guessing which case is ready. Our drink now list flags the wines that have arrived at their window, so you open them at the top rather than a decade late.