The pop of the cork, the fizz of the pour, and the clink of champagne flutes toasting are the ingredients for a celebration in many parts of the world. champagne itself dates back to Ancient Rome, but the biggest advances in the modern form of the beverage came from a savvy trio of women from the Champagne region of northeastern France in the 19th century.
Now, scientists are adding another chapter to champagne’s bubbly history by discovering why the little effervescent bubbles of joy fizz upwards in a straight line.
[Related: Popping a champagne cork creates supersonic shockwaves.]
In a study published May 3 in the journal Physical Review Fluids, a team found that the stable bubble chains in champagne and other sparkling wines occur because of ingredients in it that act similar to soap-like compounds called surfactants. The surfactant-like molecules help reduce the tensions between the liquid and the gas bubbles, creating the smooth rise to the top.
In this new study, a team conducted both numerical and physical experiments on four carbonated drinks to investigate the stability of the bubble chains. Depending on the drink, the fluid mechanics are quite different. For example, champagne and sparkling wine have gas bubbles that continuously appear to rise rapidly to the top of the glass in a single-file line like little ants—and they keep doing so for some time. In beer and soda, the bubbles veer off to the side and the bubble chains are not as stable.
To observe the bubble chains, the team poured glasses of carbonated beverages including Pellegrino sparkling water, Tecate beer, Charles de Cazanove champagne, and a Spanish-style sparkling wine called brut.
They then filled small rectangular plexiglass containers with liquid and pumped in gas to create different kinds of bubble chains. They gradually added surfactants or increased the bubble size. They found that the larger bubbles could become stable even without the surfactants. When they kept a fixed bubble size with only added surfactants, the chains could go from unstable to stable.
The authors found that the stability of the bubbles is actually impacted by the size of the bubbles themselves. The chains with large bubbles have a wake similar to that of bubbles with contaminants, which leads to a smooth rise and stable chains.
“The theory is that in Champagne these contaminants that act as surfactants are the good stuff,” co-author and Brown University engineer Roberto Zenit said in a statement. “These protein molecules that give flavor and uniqueness to the liquid are what makes the bubbles chains they produce stable.”
Since bubbles are always pretty small in drinks, surfactants are the key ingredient to producing the straight and stable chains we see in champagne. While beer also contains surfactant-like molecules, the bubbles can rise in straight chains or not depending on the type of beer. The bubbles in carbonated water like seltzer are always unstable because there are no contaminants helping the bubbles move smoothly through the wake of the flows.
[Related: This pretty blue fog only happens in warm champagne.]
“This wake, this velocity disturbance, causes the bubbles to be knocked out,” said Zenit. “Instead of having one line, the bubbles end up going up in more of a cone.”
The findings could add a better understanding of how fluid mechanics work, particularly the formation of clusters in bubbly flow, which has economic and societal value. The global carbonated drink market was valued at a whopping $221.6 billion in 2020.
The technologies that use bubble-induced mixing, like aeration tanks at water treatment facilities and in wine making, could benefit greatly from better knowledge of how bubbles cluster, their origins, and how to predict their appearance. Understanding these flows may also help better explain ocean seeps, when methane and carbon dioxide emerge from the bottom of the ocean.
“This is the type of research that I’ve been working out for years,” said Zenit. “Most people have never seen an ocean seep or an aeration tank but most of them have had a soda, a beer or a glass of Champagne. By talking about Champagne and beer, our master plan is to make people understand that fluid mechanics is important in their daily lives.”