The acoustics of champagne bubbles may provide important information on the beverage’s quality, according to a study published November in The Journal of the Acoustical Society of America. The findings could be used for commercial quality assurance.
Champagne, the white sparkling wine typically associated with celebrations, contains its signature carbon dioxide bubbles due to a post-bottling fermentation process. One theory among champagne aficionados states that the properties of the bubbles — namely their size and rate of production — are linked to that particular drink’s quality, said Kyle Spratt, first author of the study and postdoctoral fellow at UT’s Applied Research Laboratories.
To test what kind of information on bubbles can be estimated from acoustic properties, researchers placed a small hydrophone, or underwater microphone, in samples of sparkling wines.
“Bubbles are highly resonant, they basically ring like bells, and so the presence of bubbles can have a great effect on acoustic measurements,” Spratt said. “So when we came across the commonly held notion that the size of bubbles in sparkling wine is somehow connected to the quality of wine — small bubbles being thought to be better — our first thought was to stick a hydrophone in it and listen to the sounds that are made.”
Their study primarily focused on developing measurement techniques and demonstrating that acoustic data could provide information on bubbles. They found that the sounds the hydrophone picked up were due to the formation of bubbles.
The researchers tested two types of sparkling wines: the inexpensive Cook’s California Champagne and the well-known Moet & Chandon Imperial Champagne, Pratt said. The Moet had bubbles 5 percent smaller in terms of volume. Bubbles in the more expensive champagne also tended to be more uniform in size and greater in number. Pratt said the results were from a single data point and that more research was necessary before seeing a definitive trend.
Researchers also found that champagne bubbles form differently in different containers. Champagne is traditionally drunk out of champagne flutes, which are glasses that are tall and tapered to prevent the drink from warming or losing its carbonation. When researchers tested champagne in plastic foam and plastic containers, they found that the bubble formation was affected by the shape and material of the container.
“An extreme example that we showed was a plastic foam cup, in which case the bubbles stick to the edges longer and coalesce before breaking off and rising to the top, so the end effect is that there are many fewer bubbles overall and they are much bigger than in a glass flute,” Spratt said. “I don’t know whether this changes the taste per se, but it definitely changes the experience of drinking it, particularly when you are taking a sip and your nose is near the surface, experiencing the tickling sensation from all of the bubbles popping at the surface and the aroma that is produced.”
The next step is to test a variety of sparkling wines to see if there exists a correlation between bubble size and quality.
“Since taking acoustic measurements of the bubbles is a relatively simple thing to do, it could possibly be useful for quality assurance purposes for wine producers,” Spratt said. “It’s essentially an easy way to double-check that the bubbles in a certain batch of wine are behaving as expected.”