The Physics of Champagne
Champagne is a multicomponent hydroalcoholic system supersaturated with dissolved CO2 gas molecules formed together with ethanol during the second fermentation process.
Better Bubbles: Did you know that a bottle of champagne (0.75 L) holds about 10 g/L of dissolved CO2. When uncorked, this equals 9 L of gas (6 times the volume of the bottle!) which quickly escapes the supersaturated liquid to form a new thermodynamic equilibrium with air. The quality of champagne is determined by the fineness and abundance of effervescence: the bubbles tickle mechanoreceptors and taste buds in our mouth and carry volatile aromatics to our nose.
Tradition vs. Science: In bars and restaurants, champagne is poured vertically to hit the bottom of the glass, providing a thick head of foam, which quickly extends up and then progressively collapses during serving. But if champagne is poured like beer, it flows along the inclined edge and progressively fills the flute. Infrared thermography (left image) and measurement of dissolved CO2 (right image), showed that the beer-like method is best, but this scientifically validated method has not been adopted because of prejudice associated with the more plebian beer.
Chill It: The colder the champagne, the more dissolved CO2 is retained during the pouring step, as seen in the graph.
Flute or Coupe?: Measurements of CO2 fluxes outgassing from glasses showed significantly higher losses in the coupe than in the flute, providing analytical proof that the flute prolongs the drink’s chill and helps it to retain its effervescence, in contrast with the wide, broad brimmed coupe.
The Glug-Glug Effect: The first few glasses of champagne have less dissolved CO2, so be gracious and wait your turn! This turns out to be due to the onomatopoeic “glug–glug” effect caused by the liquid first flowing rather chaotically out of the bottle, through a succession of jets of liquid and admissions of air bubble, inexorably accelerating the loss of dissolved CO2 concentration through turbulences and bubble entrapment. Later, as the bottle fills with air, the champagne flows out more smoothly retaining more CO2.
References: On the losses of dissolved CO(2) during champagne serving.
Liger-Belair et al., 2010 J Agric Food Chem. 58:8768-75.
Monitoring gaseous CO2 and ethanol above champagne glasses: flute versus coupe, and the role of temperature. Liger-Belair et al.,2012 PLoS One. 7:e30628.
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