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Instant insight: Lovely bubbly
05 September 2008
Gérard Liger-Belair, University of Reims Champagne-Ardenne, France, celebrates what gives champagne its sparkle
Since the time of the Benedictine monk Dom Pierre Perignon (1638-1715) champagne is the wine of celebration. With its image inextricably linked to the elegance of its effervescence - the small bubbles it emits.
In champagne and sparkling wines, carbon dioxide molecules form in excess during a unique second fermentation process. And once opened, champagne in a typical 0.75 litre bottle releases approximately five litres of CO2. This equates to a huge 20 million bubbles formed per bottle.
A standard bottle of champagne releases 20 million bubbles
Bubbles do not just appear as champagne is poured, the dissolved CO2 molecules must be able to group together and push their way through the liquid molecules. Energetically this is not easy, and close inspection of glasses filled with champagne shows that most of the bubble nucleation (growth) sites are pre-existing gas cavities on the surface of the glass. These gas cavities are trapped inside cellulose fibres on the surface of the glass, that come from the surrounding air or from wiping the glass with a cloth before use.
Without bubbles champagne would be unrecognisable, sparkling wines and beers would be flat. However, the role of effervescence is suspected to go far beyond the sole aesthetical point of view. Bubbles bursting at the liquid surface radiate hundreds of tiny liquid jets which quickly break up into a multitude of tiny droplets every second. Those tiny droplets, ejected up to several centimetres above the liquid surface, partly evaporate, thus accelerating the transfer of volatile organic compounds and enhancing the flavour profile of the wine.
Who would have imagined that a flute of champagne is such a fantastic playground for a chemical physicist in love with microphotography, or for a champagne lover with the time and knowledge to reflect on what is happening right under his nose?
Read Gérard Liger-Belair's critical review 'Recent advances in the science of champagne bubbles' in issue 11, 2008 of Chemical Society Reviews.
Link to journal article
Recent advances in the science of champagne bubbles
Gérard Liger-Belair, Guillaume Polidori and Philippe Jeandet, Chem. Soc. Rev., 2008, 37, 2490
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