Specialistpainphysio: Champagne fizzles out if served with a splash

Not the best way to pour champagne.Carlos Alvarez / iStockphoto
If you want to enjoy champagne to the full, pour it out as you would a beer.

Sommeliers and connoisseurs may find the suggestion hard to swallow, but the evidence published in the Journal of Agricultural and Food Chemistry¹ seems irrefutable. Pouring champagne into a tilted glass helps it to retain the dissolved gas that is vital for the gustatory experience, say Gérard Liger-Belair and his colleagues at the University of Reims in France.

The French team compared the amount of dissolved carbon dioxide in a fresh flute of champagne poured the traditional way — splashing it into a vertical glass — with that after pouring along the inside of a tilted glass, as one does with beer to avoid giving it too much frothy 'head'. The researchers found that champagne served chilled (at 4 °C) contains about twice as much dissolved CO₂ using the beer-like method.

A typical 75-cubic-centimetre bottle of champagne contains five litres of dissolved CO₂. When uncorked, the release of pressure means that the liquid becomes supersaturated with the gas, which then begins to escape as bubbles. These contribute to the pleasure of drinking champagne in several ways: they give it a lively appearance, release aromas (the 'nose'), produce the stimulating oral sensation of collapsing bubbles, and create sharp tang owing to the conversion of CO₂ to carbonic acid inside the mouth.

"CO₂ has a strong effect on the sensory experience and flavour of champagne," says Susan Ebeler, an analytical chemist and oenologist at the University of California, Davis. "Flavour is a multisensory experience, including aroma, taste, colour, mouth-feel and even auditory cues. CO₂ can affect many of these senses."

Cold comfort
The slower a glass of bubbly releases its CO₂, the longer it remains vivacious. Yet it turns out that most CO₂ is lost not through bubbles bursting but by simple diffusion across the liquid surface. That is why flutes are used in the first place: the narrow neck reduces the surface area from which gas can escape.

Tilting the glass helps to keep more carbon dioxide in solution.Gérard Liger-Belair / American Chemical Society
Pouring has a big influence on the gas content, both because the 'tongue' of liquid falling from the bottle to the glass exposes a large surface area and because turbulence and entrapment of air bubbles as the liquid hits the glass can speed up diffusion of CO₂ out of solution.

The beer-pouring action should cut CO₂ loss on both counts: the column of flowing liquid is less exposed to air, and the gentler impact reduces turbulence. Liger-Belair and his colleagues have confirmed this, using a standard method for measuring dissolved CO₂ concentrations (based on the activity of the enzyme carbonic anhydrase, which reacts with carbonic acid), and using a method called thermography, which provides snapshots of CO₂ levels in air based on how strongly it absorbs infrared radiation.

The researchers also show that both to maximize CO₂ retention and to obtain the full benefits of the beer-pouring technique, the champagne must be chilled. When served at close to room temperature (18 °C), champagne served by the beer technique loses about two and a half times more CO₂ than when chilled — almost as much as it loses when served in the traditional way at room temperature.

Liger-Belair and his team show that increased gas loss from warm champagne is mostly a result of two factors. First, the colder liquid is more viscous, and so gas-leaking turbulence is dampened more quickly. Second, CO₂ molecules diffuse slowler in cold water, and so are unable to reach the surface as quickly.

Will champagne lovers be persuaded to alter their ways? "Champagne is a universe full of traditions," says Liger–Belair, who has worked as a consultant for the research department of Moët & Chandon. "But maybe champagne and science can mix to offer a better way of tasting," he says. He has at least one convert already. "Based on this paper, I probably will pour using the beer-like method now," says Ebeler.

References

Liger–Belair, G. et al. J. Agric. Food Chem. advance online publication doi:10.1021/jf101239w (2010).