Wines from the Champagne region originally were non-bubbly white wines, with effervescence viewed as a flaw. This “flaw” in the beverage later became its greatest quality. The first to be seduced by this naturally sparkling wine were the English, who were also the inventors of the modern glass wine bottle.
Nowadays, wine-lovers and tasters look for the very small bubbles that rise in columns from the bottom of the glass. The optimal size of these bubbles is 16 to 40 microns, and this may be measured using a calibrated image analysis system after a high-definition camera shot is taken.
The science behind the fineness of bubbles
Champagne bubbles are generated by carbon dioxide dissolved in the liquid. Opening a bottle lowers the pressure in the liquid, causing the CO2 molecules to loosen, expand and rise to the wine’s surface.
While it is said that the best champagnes are those that produce the smallest bubbles, this relationship is really due to the quantity of CO2 in the bottle. Since vintage champagnes are kept longer, they lose some of their CO2 because of the stopper, which is never completely airtight, and this reduces the size of their bubbles.
Distribution of bubble diameter measured by image analysis
This type of analysis, which helps determine not only the bubbles’ diameter but also their surface, sphericity and roundness, may also be used in many other industries such as food, cosmetics, pharmaceuticals and plastics.
Detecting bubbles by binarization
This objective way of assessing the quality of a champagne does have its limits. The visual appearance of the bubbles is just one of the criteria taken into account by experts, the other notable factors being taste and aroma.
Gérard Liger-Belair, Effervescence : La science du champagne, Odile Jacob, 2006