Lightstrike, a frequently encountered wine flaw, often goes unnoticed by many. In this article, we provide comprehensive insights into the phenomenon of lightstrike in wine. We will delve into its causes, preventive measures, and, crucially, offer guidance on identifying this issue. (Sometimes it smells like stinky cabbage – yuck!) Additionally, we’ll introduce a simple at-home test to learn what it tastes like so you can detect it. Furthermore, we’ll explore the types of wines most susceptible to lightstrike and offer tips for selecting wines that are free from it. So by the end of this post, we’ll completely safeguard your wine-drinking experience!
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Lightstrike in a nutshell
Smells like:
- in the early formation of lightstrike development, only the primary fruit is missing from the aromas. This makes it really difficult to spot
- then it develops stinky aromas of dishwater, cooked cabbage, wet wool, onion, egg, damp cardboard or sewage
Looks like:
- most wines have no colour change at all – again making this common fault difficult to spot
- but colour may be dull
- or worse, wines may turn yellow or brown tinged
Tastes like:
- first, the primary fruit is missing from the flavours. This makes it really difficult to spot
- then it develops awful flavours just like the aromas on the nose: dishwater, cooked cabbage, wet wool, onion, egg, damp cardboard or sewage
How wines get lightstrike:
- lightstrike occurs simply by sitting under UV light
- wines are tainted in the bottling line, on your countertop or on supermarket shelves
The types of wine that are most susceptible:
- sparkling wines, white wines and pale rosé wines are especially susceptible to UV light
- wines that are in clear glass bottles have almost no protection from lightstrike
How to prevent lightstrike:
- store your wines in a cool dark place (like a basement cellar).
- use LED lights instead of UV lights or sunlight to see your stored wines
- Read SommTips below for ways to reduce the likelihood you’ll buy a bottle ruined by lightstrike
Lightstrike, the complete story...
Lightstrike occurs when wines are exposed to too much UV light and/or blue light. When this happens, the wine produces volatile sulphur compounds which are smelly smells.
For those of you who like detail, it’s like this…
Light reacts with riboflavin in the wine and photo-oxidizes methionine (a sulphur-containing amino acid also present in wine). When this happens, the reaction forms undesirable sulphur compounds such as dimethyl disulfide (or DMDS for short).
Moreover, a secondary reaction can also see light react with tartaric acid in the wine to form glyoxylic acid and hydrogen peroxide. This response contributes to the accumulation of yellow and brown pigments and changes the wines’ colour. In both cases, the effect is irreversible.
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Is lightstrike harmful to drink? Luckily, the answer is no.
Wines with lightsrike are not harmful to you at all. At low levels, they are just not as pleasurable to drink – leaving you without a lasting impression or reason to buy the wine again. At higher levels, the wine will totally stink (see below) and ruin the experience completely.
How to spot lightstrike at high levels...
It’s pretty easy to spot faulted wines when they are badly affected by lightstrike. The wines can smell and taste of cooked cabbage, onion, smelly cheese, damp cardboard or raw sewage.
Did you know?
Wines with lightstrike can also smell of wet wool. But make sure you don’t confuse the negative wet wool aroma of lightstrike with wines that are supposed to smell like wet wool. For example, wines made from Chenin Blanc have a wet wool aroma from the grape – and this is a good thing. Therefore, Chenin Blanc from South Africa or bottles that say Vouvray, or Savennières from the Loire Valley are known for their aromas and flavours of wet wool. Don’t mix it up!!
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At low levels, lightstrike does the same thing as most other wine faults. It cancels out the fruit.
Here’s why that’s tricky to spot. You have to know what the fruit of the wine is supposed to taste like before you know it’s missing.
Moreover, with delicate flavoured wines such as Champagne, this is really difficult to do. You need to seek those soft fruit aromas and flavours of lemon juice, lemon curd, or apple/ quince fruit.
But it’s even trickier than this!
When the wine IS faulted, you will still be able to taste the winemaking or secondary aromas and flavours. In Champagne, that means you’ll smell and taste the struck match aromas, light toast, brioche, or freshly baked bread aromas from the autolysis winemaking process. You will also be able to taste the light almond nuttiness in the mid-palate and yeast from the lees ageing.
Still, that lemon juice, lemon custard and apple/ quince fruit will be missing. With wine faults, you often can’t taste the fruit leaving you with a dissatisfied feeling.
There are other secondary aromas that will fool you into thinking the wine is ok when it isn’t. For example, you will still smell and taste yummy aromas and flavours from ageing wine in oak barrels – even if the wine has lightstrike. Thus, aromas and flavours such as yogurt, nutmeg, cinnamon, and clove baking spices will show nicely when a wine has low levels of lightstrike.
Therefore at low levels, It’s common for people to assume they just don’t like the wine. Something about it just isn’t satisfying.
Hence, you really must train yourself to ask, “Is it possible this wine has lightstrike?” Then ask yourself, “Can I smell and taste the fruit aromas?”
Along this thread, if you want to know which fruit aromas you are supposed to smell, do a quick search for tasting notes of the wine in an app like Vivino, Delectable and Cellar Tracker.
It’s easier to spot lightstrike when you put the wine in your mouth and taste it. At first, the wine will simply lack the oomph. Upon closer questioning, you can discern that it is primary fruit flavours that are missing. It causes the wine to have no zest, no completeness, no balance.
Try this test at home...!
If you do this test, let us know in the comments section what you discovered!!
Even WSET's textbooks fail to cover lightstrike properly
Even WSET Level II in Wines textbook refers to this fault incorrectly. So if you understand lightstrike, you’ll be ahead of most wine industry professionals!
WSET doesn’t use the word, ‘lightstrike’. They use the term ‘heat damage‘ and explain that if the wine is too hot, in direct sunlight or under bright artificial lights, it will become damaged.
But they are mixing up 2 different wine faults.
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Heat damage is NOT lightstrike
One wine fault is heat damage. Heat damage is when the wine is heated – especially when the temperature rises quickly or rises and falls frequently. This happens easily in rooms that aren’t air conditioned in warm climates. To this point, I’ve bought wines from a Florida wine store that were heat damaged.
Heat damage causes a wine to ‘cook‘. Moreover, you may even hear an old-school term for this, ‘madeirized.’ Madeirized is a term taken from the practice of intentionally heating wine in barrels under the sun in the island of Madeira, Portugal. However, when you say a wine tastes cooked or madeirized, you are refering to a wine fault and not to a wine that is meant to be heated.
How does a wine with heat damage taste and smell?
When a wine has heat damage, the fruits turn from fresh cherries or strawberries to cooked or stewed fruits. If the wine is a white wine, the wine will turn amber or brown and will taste of cooked apples or fallen apples on a field – instead of fresh apples. In fact, heat damaged wines can still taste good because they still have fruit, albeit cooked fruit. Still, heat damaged wines don’t taste the way the winemaker intended.
But a wine that is damaged from bright artificial lights or UV will not taste the same as a heat damaged wine. The problem here isn’t the heat, it’s the light and this is why we call this fault lightstrike.
Which wines are most affected by lightstrike?
Red wines are least likely to be affected by lightstrike. That’s because red wines have tannin, an essential molecule that helps red wines age well and last.
As most white wines lack tannin, they are much more susceptible to UV light than their beefy red counterparts. Furthermore, those pretty pale coloured rosé wines, are highly susceptible to lightstrike as they have very little contact with grapeskins and very little tannin and tend to oxidize quickly.
In fact, lightstrike most often affects white and rosé sparkling wines. The off-aromas and flavours produced by lightstrike are exacerbated by the bubbles in the wine. So I guess that means that rosé coloured sparkling wines are the most susceptible to lightstrike issues.
Making the problem worse, those clear glass bottles (pictured left) fail to protect wines from UV light. (Read more on the problems with clear glass in the section below on ‘advancements in technology’.)
[Want to learn How to Become a Food Pairing Guru in 6 Easy Steps? Click here.]
[Here are the 5 Best Ways to Order Wine Online.]
[If you would like to learn about the differences between Cava, Champagne and Prosecco, read our sparkling wine guide here.]
How to prevent lightstrike?
Good wine preservation is why cellars are often dark, cold places below ground. It’s not just sunlight that emits damaging UV light, fluorescent lightbulbs and traditional incandescent lightbulbs are often the culprit behind the blue rays of UV light.
That’s why they recommend LED (light emitting diodes) lights for wine cellars as they generally do not emit UV. As an added bonus, LED’s give off a minimal amount of heat.
Of course, even if you are diligent in keeping your wines out of the light, the wines could have been spoiled previously. Researchers have discovered that the bottling line is where some wines may be damaged by light exposure.
More frequently, wines are most often exposed in shops, bars, restaurants and supermarkets. Bright lit supermarket isles and wine display cabinets showcase wine bottles with light to draw attention to the wines.
How advancements in technology can reduce lightstrike...
By using coloured glass for wine, producers can prevent lightstrike. In fact, clear glass only protects wine from 10% of the harmful light; green glass 50%, and unfashionable amber glass offers 90% protection.
Furthermore, most wine professionals are still unaware of the problem of lightstrike. In this vein, marketing departments will put pressure on producers to bottle wines in clear glass bottles. Clear glass sells!
My advice?
Ask yourself if the wine smells or tastes of lightstrike when tasting wine is in clear glass bottles!
Problems with uncoloured glass
One study of glass bottles on supermarket shelves, found that lightstrike occured in some wines in clear bottles after just 1-2 days. But all of them developed the fault after 20-40 days. The green glass offered protection for up to 50 days.
On the other hand, volatile sulphur components (stinky stuff) can be formed even within 1 hour of exposure.
Lightweighting bottles
It’s a double-edged sword when we talk about a wine-packaging trend called ‘lightweighting‘.
Yet unfortunately, lightweighting is terrible for preventing lightstrike.
A matter of fashion...
SommWine Tip
- when buying wines from a display fridge, pick bottles that are placed a few bottles away from the light source. Usually, this means a few rows back as the lights tend to shine on the first row. This way, you’ll lesson the chances that you get a bottle with lightstrike.
Famous Champagnes are taking note...
Guess who is taking the lead in tackling lightstrike? Champagne!
On this thread, Cristal, the cuvée prestige (top bottling) from Champagne house Louis Roederer, has a unique design. You see, Cristal is still bottled in clear glass.
Roederer made the clear glass bottles at the request of Tzar Alexander II who was afraid of being poisoned by his favourite drink. At that time, most poisons had colour. Clear glass ensures he could see it!
Therefore, Roederer has kept the clear-glass design but the bottles come with orange cellophane wrapping to protect the wine from lightstrike.
Other luxury Champagne brands take precautions to prevent lightstrike as well.
The famous Champagne house Ruinart recently launched this eco-friendly ‘Second Skin’ for Earth Day in 2021. The special packaging protects the bottles from harmful UV light that causes lightstrike.
Other Champagne brands sell bottles in individual boxes to protect them from harmful UV light.
Unfortunately, for many wines, fashion overtakes function for bottle choice.
Therefore, if you drink white, rosé or sparkling wines, you’ve all drunk a wine spoiled by lightstrike.
Armed with the knowledge of lightstrike’s causes, prevention strategies, and recognition techniques, you’ll be better equipped to savour your favourite bottles without the interference of this common issue. As this fault happens primarily on store shelves, it’s up to YOU to know whether a bottle tastes the way it should. So, in the future, use our tip and stop buying the first wine on a shelf. And here’s to raising your glass to a future free from the shadow of lightstrike, where every sip is a delight.
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