The reverence for champagne and its effortless drinkability belies the complexity of its production. And no truer, still, is that complexity when unpacking the inner workings of its bubbly behavior once poured. Plainly, champagne bubbles are taken for granted. And that’s okay — they’re meant to be enjoyed, savored. But for those of you staring into a glass performing a beautiful perlage and wondering what’s really going on, there’s a whole world of scientific explanation ready with answers about your favorite fizzy wine.
What Makes Champagne Bubbly?
Bubbles achieved naturally (as opposed to mechanically by machine in the case of very low quality sparklers) in champagne and sparkling wines are the product of dissolved carbon dioxide in the wine. The carbon dioxide bubbles form through a process known as secondary fermentation, and the method specifically used and required in the Champagne region is called the traditional method or methode champenoise.
The traditional method relies on a low alcohol (around 9%), high acid base wine created through a primary fermentation. This base wine is then transferred to bottles, each with a small amount added of a sugar, yeast and wine slurry – the liqueur de tirage. This solution kickstarts the secondary fermentation in which a few more degrees of alcohol are created and carbon dioxide. With the champagne bottles sealed and kept in a cool environment, the CO2 gas is absorbed into the wine.
Why Champagne Pops
There’s a law in physical chemistry called Henry’s Law that forms the basis of explanation for why champagne pops when it’s opened. It states that the amount of dissolved gas in a liquid must be proportional to the pressure above the liquid. In terms of champagne and other sparkling wines, this means that inside the bottle there is equilibrium between the dissolved carbon dioxide in the wine and the pressurized pocket of air above the liquid and below the cork. Once the cork is removed, the pressure in that itty bitty space releases, and in order for the wine to maintain equilibrium it, too, must release pressure; it does so by forming bubbles of carbon dioxide that rise and release.
You may have been cautioned in the past never to open a warm bottle of champagne – that it will open much more forcefully than a fully chilled bottle. The reason for this is also embedded in Henry’s Law: the solubility of liquid increases the lower its temperature. Translation? Cold champagne readily absorbs and maintains much more carbon dioxide than warm champagne. In a warm champagne bottle the pressure will be higher because the carbon dioxide cannot dissolve into the wine, and when it’s opened, that pressure makes itself known.
Getting the Most Bubble for Your Buck
We know it’s tempting to want to honor the celebratory spirit with a big ol’ “shake & pop,” but it’s really one of the worst things you can do to a precious bottle of champagne. Not only does it result in the loss of wine and promote the release of way more CO2 than necessary, but it exposes the remainder of the champagne to excessive oxygen which can dampen the wine’s aroma and flavor.
In addition to saving the cork launching display for, er, prosecco maybe, there are a few other tricks to maintaining the most bubbles in your champagne. Number one, always and forever, is keep the bottle chilled. If you plan on opening it and finishing it, no need to use a chiller if you’re curious about the evolution of the wine as it warms up. But if there’s any doubt about drinking it all at once do not let it warm up, else it’ll be good riddance to your bubbles. The second thing is to mind your pouring – do so at an angle down the side of a titled glass. Use non-plastic vessels (but really anything but glass or crystal is best avoided) and aim for glass shapes that have narrower mouths (i.e. not coupes).
The Magic of Champagne Bubbles
Champagne bubbles do a lot more than make us feel glittery and glamorous while drinking them. They bring invigoration to the tasting experience by activating nerve endings on the tongue. And with those energetic bursts also come the aromas of the wine. Carbon dioxide encapsulates volatile compounds and carries them through the wine right to our senses. As the bubbles rise to the surface of the wine they burst, delivering tiny punches of aromas to dip our noses in and enhancing the champagne
Additionally, effervescence – in any sparkling wine – makes for a potentially very dynamic tasting experience. Typically there is reliably only one factor that dramatically shifts the experience of a wine, and that is temperature: taste the wine chilled, taste the wine at ambient temperature. But the dissipation of bubbles as the a bottle remains open and simultaneously warms offers the experience to taste champagne in a completely different, often just as beautiful, light. Last but not least, carbon dioxide acts as a minor preservative in wine, maybe helping to extend the life of the bottle just enough to really push it to magnificence.
So much of the nuance we now understand about champagne’s bubble behavior can be credited to French chemical physicist Gérard Liger-Belair and his research teams. Liger-Belair has devoutly studied champagne, often with the use of highly specialized photographic cameras, for two decades. His findings answer questions like why bubble size varies and how to control it (no, smaller bubbles are not a sign of quality), why they form, their velocity leaving the glass, how their unique popping activity affects the aromas, and so much more…. If you’re curious to dive deeper into these topics, definitely pick up a copy of his book Uncorked: The Science of Champagne to pair with your next glass.