GWH Blog

Wine Bottles: The Importance of Glass Color for Wine

W ine bottles come in a variety of colors; glass is generally available in shades of green, brown, or clear. One may think that as a winemaker you base your color choice on preference, but this is not always the case. Winemakers will consider several factors when choosing between the colors of wine bottles. One balances his or her decision between the best practices in aesthetics (packaging), whether or not you want to showcase the wine color, the desired level of UV protection, and any consumer expectations such as traditional European bottling concepts. The considerations can be summed up as follows:

  1. Marketing (design/aesthetics/showcasing wine color)
  2. Tradition (European traditional references)
  3. Wine Integrity (UV protection of the wine)
  4. And/or some balance between marketing, tradition, and wine integrity

Traditional European Uses

Traditional European bottle shapes and colors play significant roles in the wine industry; in effect, many winemakers base their glass color selection on tradition. If one is making Cabernet Sauvignon in California, he or she may want to choose a bottle that reflects the wine’s European counterpart, such as Bordeaux, which can be an effective marketing tool that connects the consumer to their inspiration. If you’re basing your decision on tradition, you might want to reference the glass colors of France and Germany.

Green is the standard glass color of wine bottles from Champagne, France. White wines from the Mosel region in Germany are bottled in Champagne green glass too, but white wines from the Rheingau are bottled in amber (brown) glass. Antique green (amber/green) is commonly used for French Bordeaux wines such as Cabernet Sauvignon, Cabernet Franc, Merlot and other reds. On the other hand, dead leaf green or antique green is the traditional glass color for French Burgundian Chardonnay and Pinot Noir.

Glass bottle color is an important consideration when deciding how to bottle your wine.

Antique Green wine bottles line up and await bottling.

Marketing

One may prefer to base their choice of glass color on visual aesthetics, design, and packaging. Some winemakers choose a bottle based on the color schemes associated with the label design, or the choice may be based on a presentation that fits a given marketing goal. Occasionally, we even see blue bottles! This seems to be driven by marketing. Flint/clear bottles may fit in this category because the clear glass displays the color of the wine, which could be considered a marketing goal. After all, presentation and sales are certainly an important aspect to the wine business, and this should certainly be a factor.

Wine Integrity

Wine integrity is probably the most important consideration to make when choosing between glass colors. One will need to choose between a clear bottle that displays the wine color or a dark bottle color that provides UV protection. Not only is wine sensitive to both sunlight and fluorescent light, but an hour of sunlight can change the flavor of a wine and produce off-flavors, which are sometimes called lightstruck flavors.

A photochemical reaction occurs in wine after exposure to light wavelengths between 350-500 nanometers (nm), and most damage happens when exposed to 370- 440 nm. Light wavelengths can pass through the glass of a wine bottle and stimulate the riboflavin that’s naturally present in wine. The wine contains about 0.4mg/liter of riboflavin; cysteine and methionine amino acids are present in wine at about 1-4 g/liter. Once riboflavin is stimulated, it reacts with the cysteine and methionine to form hydrogen sulphide and mercaptans or 3-methyl-2-butene-1-thiol (MBT). You want to avoid mercaptans because they have the unpleasant lightstruck flavors of rotting leaves, cooked cabbage, leek, onion, skunk, wet wool, soy etc. Since humans are flavor and aroma sensitive to mercaptans at about 4 ng/liter, these products are really overpowering, and winemakers try to minimize them by choosing colors of glass that offer different levels of UV protection.

Spectrum of UV and Visible light

Spectrum of UV and visible light with a focus on the UV light that is responsible for causing the lightstruck character in wine. (photo courtesy of www.seoulviosys.com).

Certain varieties of grape, certain wine styles, and wines that have more amino acids or hydrogen disulphide (H2S) are more at risk to develop off-flavors. Lees-aged sparkling wines may be more susceptible to developing lightstruck flavors because of the contribution from the lees and dead yeast cells. For this reason, sparkling wine is rarely bottled in clear glass. Since aromatic and neutral white wines are delicate, you can taste any off flavors more easily. A wine with a small amount of H2S in it at bottling can develop mercaptan in the bottle, too.

Flint/Clear Glass

If one chooses to display the nuances of their wine’s color in flint/clear glass, then they will have the most challenges. Consumers may expect to see the color of Rosé, Sauvignon Blanc, or Pinot Grigio through flint/clear glass. It’s important to use flint/clear glass with caution because tests prove that even short-term exposure to sunlight can cause damage to wine, especially white wine or sparkling wine.

At 10% UV wavelength filtration, clear/flint bottles filter the least amount of light, resulting in more light damage than other glass colors. Since 10% isn’t really UV protection, wines bottled in flint/clear glass are meant for immediate use. Tests on white and sparkling wines bottled in flint/clear glass and trials show that citrus aromas in wines decrease and off-flavors increase after only 3.3 – 3.4 hours of exposure to fluorescent lights. During the tests the lights were placed significantly closer to the wine bottles than normal winery or display conditions, so the testing conditions were pretty extreme. On the other hand, sunlight has 4286 times the amount of UV-A radiation than fluorescent lamps, so sunlight would have increased the amount of cooked cabbage, leek, onion, and skunk aromas! Some wineries use boxes and cellophane wraps to protect wine that is bottled in clear bottles.

Three Shades of Green

Champagne Green is a vibrant green in color and is coined such because of its dominate use in the Champagne region of France. Green does not provide 100% UV protection. The darkest green glass, Champagne green (Champagne, Germany, Austria) filters out only 63% and up to 92% of the light wavelengths. Winemakers whose primary focus is to protect their wine against UV, instead of marketing considerations, bottle their wine in dark green or amber glass. Winemakers in the California wine industry tend to use Champagne green glass for popular wines including Chardonnay and Cabernet Sauvignon.

Antique green is a darker shade of green. glass is very popular in the U.S. and provides UV protection from fading or oxidation too. Red wine is somewhat protected by high tannins that bind the riboflavin, and the darker the glass the more protection it provides during aging. As we mentioned earlier, it’s the traditional glass color for red wines that need to age including the red wines from Bordeaux, France and some red wines from Burgundy, France.

The third shade of green is dead leaf green (light yellow). This shade of green provides some UV protection and is traditionally used for white wines. As we mentioned earlier, it’s one of the traditional glass colors for wines from Burgundy, France.

Light transmission through glass color by wavelength

Light transmission through glass color by wavelength (photo courtesy of Glass Technology Services).

Amber Brown Glass

Amber/brown glass (as referenced earlier) filters out 97-98% of the light wavelengths and offers the best protection but is rarely used outside of the Rhine region in Germany. If wineries were always basing their decision on the glass that best protects their wine, one would imagine us to see many more examples of these bottles. This shows that marketing or other factors can be a strong driver of winemaking decisions.

Conclusion

The choice of color for a wine bottle depends on several considerations and each winery makes unique and custom decisions that are right for their brand. One needs to decide how to balance their priorities between marketing, tradition, wine integrity, and/or a combination of the best practices in each area. The ultimate decision is yours—enjoy the choices!