It has long been said by the cognoscenti that the key to a perfect glass of champagne is a steady stream of tiny bubbles rising to the surface.
Scientists based in the heart of France’s Champagne-Ardenne region have found that larger bubbles may actually improve the way a sparkling wine tastes.
They have discovered that the presence of larger bubbles, around 3.4mm across at the surface, greatly enhances the release of aerosols into the air above the glass.
Ironically bubbles the size of those found in cheaper cava and prosecco sparkling wines lend themselves better to maximising champagne’s delicate flavours.
The effect of the larger bubbles is to drive the important aromatic compounds that give champagne its distinctive smell and flavour upwards into the drinker’s nose when they take a sip.
Professor Gérard Liger-Belair, a chemical physicist at the University of Reims, who led the research, said: “This result is also remarkable as it undermines the popular belief that the smaller the bubbles, the better the champagne. Small bubbles were the worst in terms of aroma release.”
Some one million bubbles form in the average glass of champagne, due to the dissolved carbon dioxide which forms in the wine due to a second fermentation process that occurs during production inside the sealed bottles.
When the bottle is opened, this gas is released, often explosively, causing the champagne to foam. The remaining gas then gradually bubbles to the surface in the glass.
These bubbles form a “raft” on the surface and then collapse, releasing a cloud of tiny droplets that produce the pleasurable experience when drinking champagne.
Using high-speed photography and imaging techniques, Professor Liger-Belair and his colleagues have been able to observe precisely what happens to a champagne bubble.
In a study published in the European Physical Journal Special Topics, they show that the bubbles form a regular hexagonal pattern on the surface.
When a bubble collapses, it creates a cavity that stretches and strains the neighbouring bubbles, producing a pattern that looks similar to the petals of a flower.
According to Professor Liger-Belair and his team, this increases the chances of the surrounding bubbles collapsing, creating an avalanche of tiny droplets being thrown into the air at the top of the glass.
Traditionally wine professionals often use bubble size as a marker of quality – with larger bubbles in cheap sparkling wines like prosecco and cava.
Professor Liger-Belair said bubble size in champagne and sparkling wine can vary from between 0.4mm and 4mm across. The viscosity of the drink and the glass into which it is poured can all influence how big these bubbles are.
But they found that bubbles with a radius of 1.7mm across resulted in the highest number of droplets evaporating at the surface of the drink.
He said: “We showed that decreasing champagne viscosity would improve drop evaporation.
“Additives that would change wine viscosity without changing the taste might be used. These results pave the way towards fine tuning of champagne aroma diffusion.”
Professor Liger-Belair and his colleagues have previously published research showing that chilling champagne can help to reduce the amount of alcohol carried up in each bubble. This can prevent more delicate flavours from being overpowered.
Cooling a bottle of champagne to 39°F (4°C) can also help to reduce the speed of the cork as it leaves the bottle, preventing accidents, they found.
Tilting the glass when pouring can also help prevent it from overflowing and drinking from a flute rather than a wider coupe glass can help to enhance the flavour due to the way the bubbles mix in a glass.
Professor Liger-Belair said: “Bubbles in a glass of champagne may seem like the acme of frivolity to most people, but in fact they may be considered a fantastic playground for any fluid physicist.”
By: Patrick Sawer