Why Are Wine Bottles Usually Green?

Most wine bottles are green. Is it because they're pretty? Or do they protect the booze juice inside somehow?

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Have you ever been taking out your recycling and you look at all those wine bottles in the bin and ask yourself, "Wait... why are these all green?"

Well the simple answer is that green glass is the most common packaging format for wine bottles. Some of them are clear, amber or even blue... but for the most part they're green. But why?

In 2008 the Waste and Resources Action Program charity published a report trying to reduce the volume of wasteful packaging in the United Kingdom. And they found some interesting data on wine, glass and ultraviolet light.

Exposure to short wavelength, ultraviolet light can elicit color changes in wine and have negative effects on its stability. Turns out it causes a chemical reaction, that forms sulphurous compounds.

"Light struck" is actually the term for the unpleasant flavor and aromas created by this reaction. It can occur within minutes and even a tiny amount of these compounds can make your wine taste like hobo box-juice.

Stay close to me now, as it turns out that certain kinds of glass can block this UV light so it doesn't turn wine into fermented Yoohoo. Winemakers have known this for several centuries before we even discovered electromagnetic radiation. So, they've traditionally stored the adult beverage in opaque containers until the bottles go up on a retailer's shelves.

And while the weight and thickness of a bottle's glass only offers minor protection for your “grape juice plus,” the color of the bottle allows different wavelengths of light to be transmitted or filtered.

So, it follows, then, that wine bottles must be green because they’re the best at protecting wine from the UV spectrum. Right?

Actually, no... they're traditionally green because that color has been the cheapest and easiest to produce in large quantities, while still being aesthetically appealing. Turns out that amber glass is actually the best protection against light, blocking more than 90% of harmful exposure. Green glass on the other hand only blocks 30-50% of the harmful light, while clear glass is the worst, only affording 10% protection.

But hey, since there haven't been a ton of customer complaints about wine in transparent containers, winemakers are probably going to stick with the ever popular green.

Just a heads up though that its not just sunlight that's a problem. Fluorescent lights in a store can ruin wine too. Some companies try to mitigate this by using filters, or adding UV-screening coatings to the bottles. But if you really want your wine to taste the way it’s meant to, maybe drink it from an amber bottle.

SOURCES:

SHORTAGE OF…GLASS?. (2008). Brand Packaging, 12(3), 4.

Duarte, I., Rotter, A., Malvestiti, A., & Silva, M. (2009). The role of glass as a barrier against the transmission of ultraviolet radiation: an experimental study. Photodermatology, Photoimmunology & Photomedicine, 25(4), 181. doi:10.1111/j.1600-0781.2009.00434.x

Rowan, C. (2001). Innovation in glass packaging. Food Engineering & Ingredients, 26(4), 30.

DUNGWORTH, D. (2012). THREE AND A HALF CENTURIES OF BOTTLE MANUFACTURE. Industrial Archaeology Review,34(1), 37. doi:10.1179/0309072812Z.0000000002

Waste and Resources Action Program Action Sheet. Assessment by Glass Technology Services and the University of Sheffield.

http://www.wrap.org.uk/content/what-we-do-1

Hartley, Andy. The Effect of Ultraviolet Light on Wine Quality. WRAP. May 2008.

Dias, D.A., Smith, T.A., Ghiggino, K.P., and Scollary, G.R. 2012. The role of light, temperature, and wine bottle colour on pigment enhancement in white wine. Food Chemistry 135: 2924-2941.