The Science of Champagne Bubbles

Champagne bubbles are a hallmark of the luxurious golden liquid. The bubbles are carbon dioxide gas, just like you find in soda or beer. Champagne comes in thick bottles because pressure keeps the carbon dioxide dissolved in the liquid. Popping the cork releases the pressure and the dissolved carbon dioxide molecules coalesce and form bubbles that rise to the surface and pop.

Why Does Champagne Have Bubbles?

The bubbles serve important functions in champagne. The bubbles themselves give champagne a rich texture. The carbon dioxide contributes a tangy flavor to the beverage. When the bubbles rise to the surface and pop, they release the wine’s aroma. But, how do the bubbles get into the bottle?

Fermentation and Bubbles

Any alcoholic beverage has the potential to be bubbly. This is because fermentation produces carbon dioxide as well as alcohol. In fermentation, yeast ferments sugar into ethanol (the kind of alcohol you can drink) and carbon dioxide. The sugar is sucrose, or table sugar. According to the overall chemical reaction for the fermentation of sucrose, each mole of sugar produces two moles of ethanol and two moles of carbon dioxide:

C₆H₁₂ → 2C₂H₅OH + 2CO₂

For some drinks, manufacturers bleed off the carbon dioxide into air. In other cases, fermentation is the first step of a process that then concentrates the alcohol through distillation. But, in beer and champagne, some of the carbon dioxide is kept.

How Champagne Is Made

Champagne, Cava, Franciacorta, and certain other wines are special because they are made using the “classic method.”

• The classic method starts with a base wine, which typically uses barely ripe grapes to ensure a high acidity. While the initial fermentation that makes this wine produces carbon dioxide, the gas isn’t kept.
• Winemakers add sugar and yeast to the base wine to produce “liqueur de tirage.”
• Sealing liqueur de tirage into bottles means a second fermentation occurs. But, this time the carbon dioxide does not escape.
• Opening the bottle releases the pressure keeping the carbon dioxide dissolves in the wine. The gas forms bubbles, which often escape forcefully. 

Maximizing Champagne Bubbles

Optimizing the bubbles in your bubbly enhances the aroma, texture, and flavor of the wine. For the best experience, chill your champagne before serving, select the best glass, and choose the preferred pouring method.

Temperature and Champagne Bubbles

Chill champagne before serving it. The cold temperature helps the carbon dioxide stay in the liquid, prolonging the bubbling once you open the bottle. But, don’t use the freezer because this can ruin the wine. The optimal chilling time is about a half an hour in the fridge. If you chill it too long, condensation forms on the bottle, which can drip back into the wine and sour the flavor.

Choosing the Best Glass

Champagne’s bubbles are its lifeblood, and the glass plays a significant role in bubble retention. The ideal glass for champagne is a ‘flute’. The flute’s long, narrow shape helps retain the wine’s carbonation and channel the flow of bubbles into a steady stream. This shape releases aroma compounds over a longer period and enhances the overall sensory experience.

The wide champagne glass or “coupe” has its place because the large surface area means lots of bubbles reach the surface at once. The result is a superior aromatic experience. But, if keeping the bubbles in the bubbly is your goal, this is not the glass for you.

A good compromise is a teardrop-shaped, which is commonly used with other sparkling wines. This shape keeps its bubbles and releases the fragrance of the wine.

But, what is most important is starting with a clean, dry glass. Any trace of detergent or dirt provides nucleation sites for bubble formation, leading to a loss of effervescence. There are some champagne glasses with etched interiors intended to optimize a steady column of bubbles.

The Best Method of Pouring Champagne

There are two methods of pouring champagne. In both cases, you start by pouring a small amount of liquid into the glass. This wets the glass and minimizes the risk of bubbles overflowing the glass as you pour.

• The Beer-Glass-Tilt: The best method for pouring champagne to maximize bubbles is a slow, angled pour. When pouring, tilt the glass at about a 45-degree angle and gently pour the champagne down the side. This method reduces the speed at which the champagne hits the bottom of the glass, decreasing the initial loss of carbon dioxide and retaining the maximum number of bubbles.
• The Classic Champagne Pour: The classic pour has the glass sitting flat on a table and you pour at a 90 degree angle and only fill the glass two-thirds to three-quarters full. This pour yields a head of foam. While it’s great for a coupe glass, where you focus on the fragrance of the wine, it’s inferior if you want to keep your bubbles.

How to Keep Champagne Bubble After You Open the Bottle

Here are some handy tips to keep your champagne fresh and bubbly after you’ve opened the bottle:

1. Re-cork Immediately: As soon as you’ve poured the glasses you need, re-cork the bottle. This helps keep the champagne’s effervescence intact.
2. Use a Champagne Stopper: A champagne stopper is even better than the original cork. It forms an airtight seal, which prevents the carbon dioxide from escaping.
3. Refrigerate Properly: Always store opened champagne in the refrigerator. Cold temperatures slow down the loss of carbon dioxide.
4. Store Upright: Contrary to how you might store unopened wine, store an open bottle of champagne upright once opened. This reduces the surface area in contact with air, thus slowing down oxidation.
5. Consume Quickly: Despite these steps, opened champagne does lose its bubbles and flavor over time. Consume it within 3-5 days.
6. Do Not Shake: Avoid shaking the bottle as it increases the speed at which carbon dioxide escapes from the champagne, making it go flat faster.

Fun and Interesting Facts About Champagne Bubbles

Here are some fun facts about champagne bubbles:

• Champagne bubbles rise and pop differently from bubbles in beer. In champagne, bubbles rise elegantly in straight lines and pop across the entire surface, like effervescent fireworks. Beer bubbles initially rise in a line, but then spread out randomly. The reason champagne bubbles rise so cleanly has to do with the chemical composition of the wine. Natural surfactants influence the surface tension, so stable bubble chains form.
• Each bottle of champagne contains approximately 49 million bubbles.
• Cooler champagne produces more bubbles. So, serve your champagne chilled to around 7-9 degrees Celsius (44-48 degrees Fahrenheit). But, don’t freeze it or the bubbles (or bottle) will burst.
• The pressure inside a champagne bottle is typically between 5-6 atmospheres, which is roughly equivalent to the pressure in a bus tire. In the early days, it was not uncommon for cellars to lose 20–90% of their bottles from bursting.
• A popped champagne cork can reach a speed of up to 40 miles per hour!
• The bubbles in champagne were once considered a fault. It was only around the 17th century that they became appreciated for their sensory contribution.
• The rim of a champagne glass is where the majority of aroma compounds are released.

References

• Atasi, O.; et al. (2023). “Presence of surfactants controls the stability of bubble chains in carbonated drinks.” Phys. Rev. Fluids. 8 (5): 053601. doi:10.1103/PhysRevFluids.8.053601
• Kladstrup, D.; Kladstrup, P. (2005). Champagne. HarperCollins. ISBN 0-06-073792-1.
• Liger-Belair, G. (2002). “La physique des bulles de champagne” [The physics of the bubbles in Champagne]. Annales de Physique. 27 (4): 1–106. doi:10.1051/anphys:2002004
• Liger-Belair, Gérard; et al. (2010). “On the Losses of Dissolved CO 2 during Champagne Serving”. Journal of Agricultural and Food Chemistry. 58 (15): 8768–8775. doi:10.1021/jf101239w
• Phillips, R. (2000). A Short History of Wine. HarperCollins. ISBN 0-06-621282-0.