Can light really affect my wine?
The short answer is that light can definitely affect wine, but we need to take a closer look at the physics and chemistry of all this to understand why and how in what is called lightning strike reactions, which can impart bad odors to wine, what the French call taste of light.
Wine is sensitive to harmful light rays, particularly ultraviolet (UV) rays from sunlight and fluorescent light; that’s why wine (and beer) is packaged in dark bottles; the best example is Porto in those familiar dark and opaque bottles. Wines packed in clear glass bottles are intended for rapid consumption and must be stored in cardboard boxes until that time.
All forms of radiation, including visible light ultraviolet (UV) rays and X-rays, have energy that is directly proportional to their frequencies or inversely proportional to their wavelengths, that is, high-frequency waves have lengths of short wave and vice versa. And the higher the energy, the greater the catalytic effect of chemical reactions in wine.
In wine, what worries are visible light and UVA rays from the sun; yes, UVA rays because research has shown that even a brief exposure of wine to the sun (UVB and UVC rays are absorbed by the atmosphere), in the order of hours, can have detrimental effects. effects. This is because UVA rays are in the 315-400 nanometer (nm) range of the electromagnetic spectrum and therefore have more energy than visible light, which is in the 400-700 nm range.
Glass acts as a filter, but clear glass offers no protection against UVA rays and visible light. Green glass offers some protection, but only half as good as amber; The dark amber glass offers almost complete protection. So why is so much wine, particularly many of the world’s ultra-premium wines, bottled in green glass? This is likely due to historical reasons, as making green colored glass was easier and the effect of radiation on wine was unknown.
But glass is only half the story. Now we must consider the optical properties of wine and then determine how radiation affects any chemical reaction.
Research has shown that wavelengths in the 375-440nm range, that is, the high end of the UVA range and the blue (low) end of the visible light range, are most damaging to wine. The amount of radiation absorbed by the wine in this range is directly proportional to the opacity; therefore, red wine absorbs more and is more affected, while white wine absorbs less rosy wine in the middle. As such, for marketing purposes where displaying color is important, white wine can be stored in clear glass, although not for long periods of time; That’s why premium whites, like aging-worthy Chablis wines, come in glass the color of dead leaves, a golden yellow color that provides better protection than green.
Deep, opaque, and richly colored reds absorb almost all radiation; however, they have the highest concentration of effect-inhibiting tannins, which provide protection. But if the concentration is low or the degree of exposure is prolonged, unpleasant and unpleasant aromas and flavors may develop. Specifically, red wine has sulfur-containing amino acids, that is, they contain methionine and cysteine, which have a thiol (sulfur-hydrogen) side chain in their structures. These then react with natural vitamins, such as riboflavin (vitamin B2) and pantothenic acid (vitamin B5), water-soluble vitamins that are easily destroyed by heat, oxygen and, that is, ultraviolet light. The products of this reaction are sulfur compounds such as hydrogen sulfide, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS), responsible for imparting a variety of foul odors, from rotten eggs to cabbage to wet dog.
Interesting science.
And now I am left wondering if my precious 1991 Château d’Yquem magnum, in a clear glass bottle, which I bought for my son born that same year, was affected by X-rays on its journey from the USA. It was earlier. As of September 11, however, the steadfast airport security guard could not be persuaded not to X-ray my precious bottle. I suppose he was not a fan of good wine.
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