Definition: champagne and effervescence

8 Questions/Answers about the effervescence of champagne...
By Gérard Liger-Belair, University of Reims.

How can the size of the bubbles be explained?
Champagne bubbles, fed by dissolved carbon dioxide, grow larger as they rise to the surface. Initially, they are microscopic and can reach a diameter of one millimetre after rising about ten centimetres, at the start of tasting. At the end of the tasting, the champagne, depleted of carbon dioxide, releases only much finer bubbles. Of course, other parameters also influence the size of the bubbles, such as serving temperature and pressure. But the main parameter remains the dissolved carbon dioxide content.

Bubbles are larger in plastic glasses. Why is this?
This is due to polyethylene, the material used to make plastic cups. This material is very hydrophobic: water does not wet it very well. The bubbles cling to the sides of the cups, as plastic prefers contact with gas to contact with liquid. The bubbles grow larger on the side of the cup, gradually sliding towards the surface. This difference in wettability between glass and plastic explains why the bubbles are fine in a glass or crystal flute and large in a plastic cup. It is also worth noting the absence of a string of bubbles in a plastic cup: to form a fine string, the bubbles must follow each other very quickly without sticking to the sides of the container.

Is it advisable to wash flutes in the dishwasher?
This is not recommended, mainly because the products used leave a thin film of detergent on the surface of the glass. This causes the bubbles on the surface to burst. The ideal method is to rinse the flutes with very hot water and dry them with a soft cloth.
What causes the sparkle above the glasses?
Hundreds of bubbles burst every second on the surface of the champagne. Each bubble causes a small jet of liquid. The surface of the champagne is thus dotted with hundreds of tiny jets that form the sparkle. It is estimated that an average of five droplets are produced per bubble that bursts.
The mist above the flute is formed of very fine droplets about 100 microns in diameter.

Beer bubbles/champagne bubbles: what is the difference?
Essentially two:
- The carbon dioxide content dissolved in beer is half that of champagne. As a result, the bubbles grow more slowly and are therefore finer than in champagne.
- Beer is richer in surface-active macromolecules, which stiffen the bubbles and extend their lifespan. This is why beer bubbles form a thick head, unlike the short-lived bubbles in champagne.
How important is serving temperature?
The higher the temperature, the faster the carbon dioxide molecules pass from the liquid to the bubbles. The effervescence is then more generous and the bubbles are larger.
Champagne served at 15°C will produce 50% more bubbles than champagne served at 5°C.

What effect does lipstick have?
Lipstick has no effect on the intensity of effervescence, but it does cause the bubbles to burst. This is because, on the surface, the bubbles are separated from the air by a thin film of liquid. The fatty substance in lipstick spreads over this film, making it thinner. Eventually, the film breaks.

The best choice: coupe or flute?
A coupe glass does not allow you to appreciate all the qualities of a champagne and obscures the path of the bubbles to the surface. However, it does promote better dispersion of the gases, diluting the aromas.
The flute is becoming increasingly popular. It allows you to appreciate the trajectory of the bubbles and concentrates the aromas released when they burst. This prolongs the effervescence of the champagne.

Our tips for serving champagne:
• Choose glasses that are large and tall enough to allow the bubbles and aromas to develop and rise to the surface.
• Check that your glasses do not contain any residue from washing-up liquid or rinse aid, which would "kill" the effervescence of the champagne. Avoid putting your flutes or coupes in the dishwasher.
• Bring the Champagne to the ideal temperature of 8 to 10°C by immersing it in water with ice cubes for 20 minutes.
• Fill the glass no more than two-thirds full so that you can enjoy the aroma.
• Allow the Champagne time to open up a little so that you can fully appreciate its richness.
Partial source: - La Vigne - No. 182 - December 2006
See also the entry "Point de mousse".
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