Does bubble size matter in sparkling wines?

Anyone who knows me knows how much I love Champagne and sparkling wines in general. But what is most intriguing to me is the science of this category of wine. So inevitably discussions at social events often lead to what type of glass is "best" for enjoying sparkling wine and does bubble size matter.

It is well known and well documented now that sparkling wine flutes are better than the traditional coupes, and this is no longer a point of contention. Science clearly demonstrates that carbon dioxide (CO2) gas loss is greater from coupes owing to the much larger opening over the glass.

But bubble size can certainly generate some lively discussions, akin to cork vs. screwcaps in still wines. Some believe that bubble size does not matter while Champagne hardliners are convinced that smaller bubbles translate into higher-quality sparkling wines, that is to say that the aromatic profile is more complex, longer lasting.

I have been following the work of Gérard Liger-Belair and his team of researchers, aptly named Team Effervescence, at the Université de Reims Champagne-Ardenne. Liger-Belair has made a career of studying the dynamics of Champagne and the impact of service on organoleptic qualities. Not a bad job! His work is absolutely fascinating, not necessarily because of the nature of the work, but rather because of his convincing methods and data. He has studied CO2 gas diffusion using a thermo-sensitive camera and bubble dynamics with a ultra-high speed camera. Anyone who has seen his work published would agree that the pictures are simply amazing.

Most recently, Liger-Belair and his team demonstrated how and why smaller bubbles are better. When bubbles rise to the surface of the wine, they "explode" into thousands of droplets, or what they call "Champagne aerosol," that create a concentrated gaseous volume over the surface and which augments volatile aromas. But glass shape, and more precisely, height of the flute and how much wine is poured, plays an important part in the sensory pleasure. As bubbles form and rise in the glass, their volume increases whilst their speed decreases. And so, a pour close to the rim would cause precious loss of Champagne aerosol, but more important, the bigger bubble volume at the time of the explosion translates into greater aroma loss. A pour somewhat lower would concentrate the aerosol and aromas, leading to greater appreciation of the wine.

The astute reader might question then why coupes, with their much shorter distance for bubble travel, are not suited for sparkling wines. It goes back to the fact that the wider opening causes a greater loss of gas and thus of aromas.

So now, those tall, thin flutes may not be the best type of glasses to serve fine bubbly. Nope. The ideal type sort of looks like a separator funnel set on a stem; some call it tulip-shaped. The ideal glass was designed by Philippe Jamesse, chef sommelier at Domaine les Crayères. The glass starts off in a V shape with a maximum diameter about two-thirds up, and then becomes a tad smaller again up to the opening. The wine would typically only be served up to the largest diameter portion of the glass, but this can depend on the type of wine being served. Then bubbles rise a much shorter distance and into tinier droplets to then concentrate the aerosol just above the surface but constrained within the upper volume of the glass. Very interesting!

Now as I prepare to uncork a fine bottle of Champagne, I'm wondering if Liger-Belair needs fresh blood in his team.

Daniel