Why champagne bubbles go straight up

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Researchers from Brown University published a study in the journal Physical Review Fluids this past week on champagne bubbles.

The scientists had been scratching their heads trying to work out why the bubbles from champagne go up in a straight line, while those in beer or other fizzy drinks rise at random.

Now they can pop the corks – because they’ve finally cracked it.

As lead researcher Professor Roberto Zenit explained, the substance that gives champagne its flavor is effectively a substance which loosens surface tension, much like soap.

“There is something within champagne, in the liquid itself, that is affecting the motion of bubbles. So what we discovered is that there are these molecules that attach to the surface of bubbles called surfactants and those molecules which in the case of champagne happen to be the good stuff, the flavor molecules,” Professor Roberto Zenit.

Not all the bubbles in carbonated or fizzy drinks behave the same way. In beer, the bubbles go in all directions.

 “Beer of course has a different flavor and a different composition and a different origin, a completely different origin from sparkling wine, so in that case those molecules are of a different kind they are proteins that are smaller and sometimes they attach to the surface and sometimes they don’t,” Zenit said.

You don’t see the bubbles in the bottles themselves because they’re under extraordinary pressure.

“Yeast produces ethanol, and it produces carbon dioxide, but since it’s enclosed in a bottle the carbon dioxide does not escape, it becomes dissolved in the liquid and as this happens as the yeast eats the sugars of the grape juices, the carbon dioxide accumulates in the liquid and that’s why the pressure in the bottle increases,” Zenit said.

The making of sparkling wine has been celebrated since it was first created by the Benedictine monk Dom Perignon in France.

The pressure that builds up during the fermentation process is finally let loose when you pop the cork.

“When you open the bottle, you change the pressure in the liquid from being six or seven atmospheres (measurement) to being just one atmosphere, you got no atmospheric pressure, so the gas – the liquid that has a lot of dissolved gas, comes out of the solution and that’s what gives rise to the formation of bubbles,” Zenit said.

There’s a good reason the movement of bubbles in sparkling wine has focused the attention of many scientists around the world.

Bubble mechanics is helping researchers to understand physics in the natural world as well as how that physics can be applied to help human society.

“That is of significant importance to understand many natural phenomena, like the way methane bubbles rise from the bottom of the ocean, or how we produce penicillin right? When you have this penicillin reactor you use bubbles because these bubbles (are) used mixing in the liquid in these bioreactors. So we are interested in what, how bubbles move in liquids because of those engineering applications and also in natural phenomena,” Zenit said.

The scientists have also been enjoying some of their research in the laboratory and Zenit admits they may have tasted a sample.

“There’s lots of that (champagne and beer) to drink anyway, but yes we did conduct experiments with actual champagne, sparkling wine and some beer, but it was just a few glasses just to test, just to demonstrate that this was the case,” he said.