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How Does Light Affect Wine? | Choosing Wine Cellar Lighting

March 30, 2020
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Scott
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Naturally present in wine are collections of chemical compounds—wine tannins arguably the most famous. When winemaking and wine storage are done correctly, those compounds are at just the right proportion to each other. No one chemical component of the wine is strong enough to throw the structure out of balance.

But when the concentration of one or more of those compounds is too strong, we can tell when we taste or smell the wine. It’s crossed the sensory threshold. That means the strength of the out-of-control compound obscures the desired aromas and flavors of the wine. When this happens, it’s known as a wine fault.

The name of the game in wine storage is preventing wine faults.

Imagine a wine bottle that’s been left in a car. One week it’s 70°F. Next week it’s 50°F. Then 75°F the following week. The inconsistent temperature causes the cork to expand and contract, ultimately losing its integrity. The bottle doesn’t leak but the cork lets in far more air than it should. (Some oxygen is good, especially before serving, which is why folks learn how to decant wine and value what wine aerators do.)

But too much oxygen is too much. The increase in oxygen exposure from a compromised cork causes so much of the wine’s ethanol to turn into acetaldehyde that the sensory threshold is exceeded. The wine now tastes more like acetaldehyde than anything else. Also known as vinegar. That’s a wine fault.

So, storing wines at consistent and optimal wine storage temperatures is one way to prevent wine faults. Another is choosing wine cellar lighting that doesn’t throw your wine’s chemical structure out of whack.

Here’s what you need to know about how light affects wine and how you can best set up your wine cellar or wine storage cabinet to protect your collection.

Wine and Light: The Basics

Does Light Affect Wine?

Yes, light affects wine. But it depends on the type of light, the strength of light, the duration of exposure, the type of wine, and the type of wine bottle the wine is in

How Light Affects Wine

Light can rearrange a wine’s chemical compounds—just like oxygen and temperature—and cause wine faults. The resulting wine is known as light-struck. That means the wine is prematurely aged and its taste, aroma, color, and mouthfeel have been irreparably changed for the worse.

This happens because light causes sulphurous compounds to form at an accelerated rate in wine. Light-struck wines, then, have funky, cooked-cabbage, wet-dog, rotten-egg, or lit-match aromas and flavor profiles that cross the sensory threshold.

Wine lingo is a joy, isn’t it?

What Type of Light Affects Wine?

Direct sunlight and electric fluorescent and UV lighting (in your wine cellar, for example) can all cause wine faults.

What Type of Wines Are Affected by Light?

While all types of wine are affected by light, the lighter the wine, the more easily it will be affected by light exposure. Red wines absorb more radiation from UV exposure. But they also have a higher concentration of tannins that minimize the impact of this exposure, though that concentration goes down with aged red wine.

What Type of Wine Bottles Are Affected by Light?

Any bottle will offer some level of protection from light exposure, but the darker the better. 

A study by Dozon and Noble found that still and sparkling wines bottled in clear glass and placed 35 centimeters away from two 40-watt fluorescent lamps showed a noticeable increase in light-struck aromas at around 3.5 hours. The same experiment with green bottles showed comparable changes after around 20–30 hours. Amber bottles, though, are found to give better protection than clear and green bottles. Clear glass is worse than green glass is worse than amber glass.

The shape of the bottle and the direction of light also have an effect. A study from the American Society of Brewing Chemistry found that, when lit from above, long-necked bottles with a shallow angle on the bottle shoulder are substantially more effective in protecting alcoholic beverages from light-struck faults.

How Much Light Is Bad for Stored Wine?

Any amount of direct light can adversely affect the quality of wine. But it’s possible to quantify the impact of time.

The study referenced above, exposing wine to two 40-watt bulbs from a close distance is atypical light exposure. The findings about bottle color are helpful. But the speed with which the wine developed faults is a function of how aggressively the wine was exposed to light. Another study tried to mimic the typical light found in a wine store. That study found that nearly all wines experienced light-struck faults after 200–500 hours.

What Type of Lighting Is Best for a Wine Cellar?

Dimmable LED lighting is the best lighting for a wine cellar. No type of lighting will remove the problem of light-driven wine faults entirely. But your best bet is to use dimmable LED lights because they give off minimal heat and can have their brightness turned down when needed. Non-LED lights, even when not in direct contact with your wines, give off a lot of heat that can change your cellar’s temperature and “cook” your wine—which is the word use for heat-related wine faults. At least you can choose lights that won’t become a variable in setting and maintaining an optimal temperature in your wine cellar.

Architect Mayur Modi, director of Knauer, Inc., leverages his 20+ years of experience in luxury home and hospitality projects when he says “we’ve been successful with narrow spots, no more than 2700K, high lumens, small aperture LED lights. The placement is key. One light above each row of wine bottles strategically placed so the labels glow, from top to bottom.”

How Can I Protect My Wine Collection from Light Exposure?

The best thing you can do to protect your wine collection from light exposure is to store it in a dark and temperature-controlled environment. While the color and type of wine bottle offers some defense against light, don’t take chances with your collection.

Some other steps you can take are wrapping bottles in cellophane to obscure light rays, or keeping wines in cardboard or wooden containers. If your wine storage is designed to show off your collection, consider looking into wine bottles with improved light-filtering properties.

Wine Cellar Lighting Do’s and Don’ts

When choosing wine cellar lighting, pay special attention to lights that provide the right amount of illumination without any of the harmful heat. While in any other room of your house, you’d place a premium on natural light, in your cellar that’s a hard no. Every sommelier class eventually covers just that. At this point, avoiding natural light is an industry standard. Similarly, any other lighting that emits UV rays, any high-intensity (high-wattage), incandescent, and halogen lights are all out of the question. 

That leaves us with the good-ol’ LED lighting. LED lights literally check off all the boxes: 

  1. Do not emit UV light
  2. Run cool and stay cool
  3. Incredibly energy efficient
  4. Cost-effective and long-lasting
  5. Many cost-effective, dimmable, and color-controlled options available

The Importance of Wine Cellar Lighting

The purpose of a wine cellar goes beyond the “cellaring” of wine or simple utilitarian wine storage. An ideal wine cellar is an homage to your wine collecting prowess and a celebration of the collection itself. It should also be organized and easy to navigate, which is why private wine collectors can benefit learning how to take wine inventory or use wine cellar apps like wine program managers. Ergo, the wine cellar must be practical, of course. But it must also provide the ideal ambiance for you and your guests to experience your collection.

At the good end of the spectrum, you’re storing amber bottles in the dark. At the bad end, you’ve got clear bottles in bright light. Anything you can do to lean toward the good end, you must. Choose darker wine bottles, and light entire rows of bottles from the top with dimmable, small-aperture LED lights.

When done right, you can shine a light on your wine collection and showcase it in all its glory. When done wrong, you can turn a $500 bottle of wine into cooked cabbage in record time.