Champagne proves a fantastic playground for physicists

The distinctive character of champagne is in large part due to the effervescence that occurs during pouring, which results from the interplay between dissolved carbon dioxide gas molecules, tiny air pockets trapped during the pouring process, and the properties of the glass. A standard bottle of champagne contains dissolved carbon dioxide equivalent to five litres of gas at atmospheric pressure which when uncorked is released to form about one hundred million bubbles about half a millimetre in diameter.

The fleeting life of champagne bubbles intrigues scientists; collapsing bubbles are common in our everyday lives but are still not fully understood. Two reviews published in the most recent issue of the journal Bubble Science, Engineering & Technology explore collapsing bubbles and bubble flow patterns in champagne glasses. These phenomena are of much wider interest because of the huge importance of bubbles in many natural and industrial processes.

The lead author of the reviews is Dr Gerard Liger-Belair of the University of Reims in Champagne-Ardenne, based at the heart of the Champagne region. He is one of a handful of physicists engaged in exploring the physics of bubbles and foam in champagne and sparkling wine. With 15 years of experience, his research has made him leader of the 'bubble team' in the University's laboratory of oenology -- wine research where -- he has studied the rise and fall of champagne bubbles from bottle to glass.

Understanding the source of the bubbles could potentially help to improve champagne production, Dr Liger comments in his second review: "From the consumer point of view, the role of effervescence is essential in champagne, sparkling wines, beers and to a great extent in any other carbonated beverage. Without bubbles, champagne would be unrecognisable as such, and beers and sodas would be flat." The author continues to say "However, the role of effervescence is suspected to go far beyond the solely aesthetical point of view."

The first review surveys the physical phenomena relating to bubble collapse on the basis of striking images obtained by high speed photography of bubbles at the top of a glass poured with champagne. It is shown how the jetting and avalanche processes linked to bursting or collapsing bubbles radiate tiny droplets and aerosols that release flavours and how rising and collapsing bubbles provide continuous lift and circulation for aromas in a glass of champagne. The authors comment that further experimental studies and numerical simulation are required to achieve further understanding of these highly complex phenomena.

The second review focuses on ascending bubble flow patterns in flute and coupe style champagne glasses and their impact on gaseous carbon dioxide and ethanol release under standard tasting conditions. It is well recognised that tasters' perceptions of wines are affected by the shape of the glass, and with champagnes are augmented by the aesthetic and sensory effects of the effervescence -- through the sensation of bubbles on the tongue and the release of flavours and aromas.