A team of scientists at the University of Reims have revealed the secrets behind the bubbles in Champagne, and why your glass might leave the wine as flat as a pancake or fizzing furiously.
The team leader, 41-year-old Gerard Liger-Belair, said: “We have made discoveries that are really exclusive to Champagne, things that have not been observed before."
A single bottle of Champagne contains 10 million bubbles. As the bubbles reach the surface of the wine they explode, and this phenomenon – known as the Worthington Jet – has been captured by the scientists on a 5000-frames-per-second camera.
"Here's a sequence of high-speed pictures of a bubble that is about to pop on the surface of the wine," explained Liger-Belair. "It explodes, making a tiny crater on the surface. The crater closes up and then ejects a thread of liquid, which then breaks up in droplets that can fly up to 10 centimeters."
Using an ultra-high-resolution mass spectrometer to analyze the chemical structure of samples, Liger-Belair's team found that a Champagne’s effervescence is laden with "tensio-active" molecules, of which hundreds are aromatic molecules. enhancing the wine's aroma.
They also figured out why strings of bubbles, known as the bead, rise from certain points in glass. It happens when microscopic fibers – left by a kitchen towel or often just an airborne particle – stick to the side of the glass, allowing molecules of dissolved carbon dioxide to coalesce and form bubbles.
The finding is important for Champagne lovers and for the restaurant industry.
Glasses that are retrieved from a dishwasher, where they have been washed and blown dry upside down, could be so ultra-clean that horribly few bubbles form.
Top-end glass manufacturers now use lasers to etch a tiny crown of spots at the bottom of the glass, creating flaws to make bubbles form and rise in a pretty ring. Champagne fans can make a few small scratches of their own – but "no more, otherwise you have a huge degassing," said Liger-Belair.
Earlier this year, Liger-Belair and his colleagues issued a devastating verdict on a debate that has raged for hundreds of years. Should you drink Champagne from a tall, long-stemmed glass – a "flute" in French? Or should it be a "coupe," the shallow cup that, according to legend, is modeled on the breast shape of Marie-Antoinette?
Gas chromatography showed that a coupe loses CO2 at least one-third faster than a flute. So unless you drink very quickly, you lose the precious effervescence.
In similar vein, drinking Champagne from a plastic cup can be a drab experience because the sides are hydrophobic, or liquid repelling. The bubbles adhere to the sides through capillary action and inflate into the size of tiny balls.
Liger-Belair's research has been published in peer-reviewed journals aimed at physicists working with fluids and beverage specialists who deal with other sparkling wines, beers and sodas.
In the Champagne region, the research has been instrumental in helping winemakers fine-tune the second fermentation in bottle.
"The easiest way to produce finer bubbles is to reduce the quantity of CO2 which is dissolved in the Champagne, and this is linked to the amount of sugar," said Liger-Belair.
The tradition was to add 24 grams of sugar per liter of Champagne along with yeast to induce the second fermentation, but the trend now is 18 grams of sugar, the lowest permissible under Champagne regulations.
"People prefer smaller bubbles, possibly because this quality is associated with vintage champagne," said Liger-Belair. The scientist reports that he has occasionally come to blows with traditionalists who believe that physics will kill the myth of Champagne.
Champagne is portrayed as a small-scale, artisanal product, a wine of ancient knowledge and "terroir" – a French word redolent of the soil.
But Philippe Jamesse, head wine waiter at a five-star Reims château, Les Crayeres, believes science and wine can go hand in hand. "When you see Gerard's work, you understand why the 'coupe' is completely outdated. We don't have any here."
So what does the scientist do with all the booze? Once the experiment is over, does he drink it?
"Unfortunately, no," said Liger-Belair. "By that time, it's warm and undrinkable. I think I must have thrown more Champagne down the sink than anyone else on this planet."