What are the impacts of light on wine conservation?
We are all well aware of the importance of maintaining optimal temperature and humidity conditions to ensure that the aging of our wines is assured. In the past couple of years, I have been able to note the importance of those elements by visiting many cellars dating back by more than millennia, accompanied by experienced professional sommeliers.
However, the majority of the proprietaries of said cellars only authorized the use of a candle as the light source while accessing the cellar. This particular element raised many questions: Why the candle? What is the negative impact of light? I decided to delve into the question and to understand the technical reasons, if they exist, of this said practice. If the light has a negative impact on wine, what is the level of protection offered by the glass of my cellars for my bottles that are consistently exposed to the light of day?
First and foremost, from a technical point of view, the visible light is constituted of a mixture of red, green and blue lights. Each of these colors is associated with an array of wavelengths. The spectrum of visible light is composed of wavelengths varying from 400 nanometers (nm) to 750 nm. Contrary to popular belief, it is relatively well known that the ultraviolet rays (wavelength < 400 nm) have a negative impact on wines. A good amount of lighting systems in our homes or in wine shops or retailers generate a non-negligible amount of UVs, just like the light of day.
In 1983, during a study conducted by Beech, wine samples were exposed to fluorescent tubes and other samples were exposed to a temperature of 26,7 Celsius (80 Fahrenheit) during a period of twenty-five weeks. Surprise! The lighting had a much bigger impact on the conservation and the taste of the wine compared to the heat. Many researchers such as Maujean and Emond, have since then confirmed the study of Beech and have concluded that it was important to block wavelength up to 523 nm in order to completely protect the wine from exposure to light.
The impact of light on wine is created by a chemical reaction. This reaction, which brings the “light taste” to wine, implies the presence of multiple composed elements, in different proportions, in all types of wines such as the amino acids containing sulfur such as methionine and cysteine.
These composed elements are documented by the scientific literature as being responsible for damages to the odor and taste done to wines by exposure to light, damages that are detectable by the average palate and often described and compared with boiled cabbage, wet dog, leek and onion.
The majority of studies that we have consulted aimed to cover wines from the Champagne region or other white wines, even if that chemical reaction is also produced in red wines. The phenol, which is present in tannins (which is also an inhibitor of the chemical reaction described above), provides much more protection to red wines when compared to white wines.
I will certainly be going over this subject in a following article, but multiple conclusions already arise. Make sure that you insist on getting a UV protection of over 450 in the glass used for the construction of your cellar. You should also favour a red incandescent lighting (or a red DEL lightning), because red lighting cannot affect or damage your wines, no matter the intensity. Finally, stay away from any form of fluorescent lighting.
President and Founder of Celliers Intelligents.
- Beech, F. W., Macpherson, Seventh Wine Subject Day on Shelf Life, 1982, Long Ashton Research Station