A cork pops. The sudden change in pressure releases carbon dioxide trapped in the bottle. Bubbles form. They ride along as liquid falls from the bottle to your champagne glass. Once inside, a million of them cling against its edges before rising to the top and bursting — like supernovas — as soon as they hit the air. The explosion releases tiny droplets of liquid, and for a moment, your mouth contains a universe. The droplets dart across it like shooting stars that crash against your tongue. The aromatic landing of the fermented grapes is sharp, crisp, sweet, dry, delicate, delightful. This may be how you welcome 2017.
At least, that’s how some scientists have done it this year. For an issue of the European Physical Journal Special Topics, to be released in January, they follow carbon dioxide from where it first becomes trapped in grapes on vines until it enters the bottle and forms, rises and eventually bursts and evaporates in your glass. Each pop along the way helps enhance the drink’s aroma.
Even though bubbles are part of our everyday lives, much about how they behave is still mysterious. By studying them in sparkling beverages, scientists learn how their basic mechanics and chemistry can be applied, from better tasting wine to more efficient energy.
The journey starts with grapes, which contain sugars on the inside and yeast on the skin. Breaking the skin kicks off a fermentation process, resulting in the release of alcohol and carbon dioxide. The gas escapes through open barrels where wine is first made.
But once wine goes inside a champagne bottle, a second fermentation process begins and the carbon dioxide is trapped by the cork. There it dissolves into the liquid, taking up space and causing pressure to build through a process called Henry’s Law. Although a bit of carbon dioxide will escape, most of it stays trapped until the bottle is uncorked, which, by the way, is also a science. For example, one study found that cooling a bottle to 39 degrees before serving causes trapped gas to expand less rapidly. That means when you pop the cork, it will fly at about three-quarters of the speed it would at room temperature.
Once inside your glass, the bubbles will start to congregate at the liquid’s surface. They touch one another, forming a hexagonal pattern. And where the liquid meets air, the bubbles burst.
Gérard Liger-Belair, a physicist at the University of Reims Champagne-Ardenne in France, and his team, which conducted one of the studies, captured this with high-speed cameras. The images showed that when one bubble burst, it left behind an empty space that others stretched out to occupy until they themselves burst, quickly resulting in a spray in the air. New bubbles moved up to the surface, where they burst and the process continued.
Thomas Séon, a physicist at Pierre and Marie Curie University in France, and his colleagues, found that each bubble’s spray contained tiny droplets full of concentrated aromas and flavors, or volatile compounds that you can smell and taste. An aroma can vary, depending on bubbling speed, a single bubble’s size, temperature of the liquid and even the shape of the glass. Some people say that tiny bubbles flowing constantly make a tastier drink, but actually, the researchers found, big bubbles do because they release more aromatic spray.
For a bubblier glass of sparking wine, allow your bottle to warm up for a little while after taking it out of the refrigerator or off the ice. Be careful — the cork from the warmer bottle might fly out faster. Pour into a narrow glass at an angle. Now sip. And as you share your newfound knowledge of bubbles with your fellow New Year’s Eve revelers, perhaps the ones who appreciate it are the ones to keep around in 2017.
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