What is lightstrike in wine?

Quick answer: what does lightstrike mean?

Lightstrike is a light-induced wine fault. In susceptible wines, exposure to ultraviolet and blue light can trigger chemical reactions that dull fresh aromas and create unpleasant sulphur-like smells.

At a simple level, light can activate compounds such as riboflavin. These may then react with sulphur-containing compounds, including methionine, producing volatile compounds associated with aromas such as cooked cabbage, onion or rotten egg. Light can also reduce desirable fruity and floral characters.

The risk depends on the wine, the bottle, the light source, how intense the exposure is and how long it lasts. It is not true that every clear bottle is damaged, or that one particular smell proves lightstrike.

Which wines and bottles are most at risk?

Lightstrike is mainly associated with bottled white and rosé wines, although that does not mean every bottle of either style is vulnerable. Sparkling wines are also discussed in the technical literature as susceptible.

Clear or flint glass generally gives less protection from relevant wavelengths than green or amber glass. Darker glass can reduce the risk, but it is not an absolute guarantee. A wine’s composition and the conditions of exposure matter too.

A bottle standing in direct sun is an obvious risk, but bright artificial lighting can also matter. Prolonged exposure in a brightly lit retail display has been associated with lightstrike in some wines. That does not mean a bottle has been spoiled simply because it was displayed under shop lights.

What does lightstrike taste or smell like?

People may describe lightstruck wine as smelling or tasting of:

• cooked cabbage;
• onion;
• rotten egg;
• vegetal or drains-like aromas; or
• muted fruit and floral aromas.

These descriptions are useful clues, not a diagnosis. Lightstrike can vary between wines, and some other faults can produce similar sulphur-like impressions. Smell alone cannot prove what has happened.

How is it different from other wine faults?

Oxidation is a separate, oxygen-related form of deterioration. It may bring bruised-apple, nutty, stale or sherry-like characters. Lightstrike is defined by light-driven reactions, not oxygen exposure.

Heat damage is primarily caused by excessive temperature. Wine exposed to too much heat may develop cooked, stewed, jammy or prematurely aged characters. A warm delivery does not prove lightstrike, although a sunny journey could involve both light and heat.

Reduction can also produce sulphur-like smells, including struck match, rubbery or cabbage-like notes. It is not the same fault as lightstrike, and the two can be difficult to distinguish by smell alone.

Cork taint is more commonly associated with musty, mouldy, damp-cellar or wet-cardboard aromas. It is not caused by light.

How can you prevent lightstrike?

Store wine in a dark place away from direct sunlight and strong artificial light. Do not leave bottles on a sunny kitchen bench, windowsill, in a hot car or somewhere exposed to bright light during delivery.

When buying wine, avoid bottles that have clearly been sitting in direct sun or intense lighting for a long time. This is a sensible precaution, not a reason to assume that all clear bottles are faulty.

If you think a bottle is affected, compare it with another bottle of the same wine if that is practical. Keep the bottle and packaging, then contact the retailer or producer. Moving the wine into darkness may prevent further exposure, but it does not reliably restore established lightstrike. Aeration, decanting, chilling or household additives should not be treated as dependable cures.

Frequently asked questions

Is lightstrike the same as sun damage?

Not exactly. Sunlight is one possible source of the relevant light, but strong artificial light can also contribute. The fault is caused by particular light-driven reactions, not simply by warmth.

Can you drink lightstruck wine?

The evidence here concerns wine quality and sensory character, not a demonstrated food-safety hazard. If the wine smells unpleasant, it is reasonable not to drink it and to contact the retailer or producer.

Does green glass prevent lightstrike?

Green or amber glass generally provides more protection than clear glass, but no bottle colour guarantees that a wine will remain unaffected.