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The small bubbles of the Cava….

Source: The blog below used parts of an article from the Dutch paper 'Het Parool' of May 11, 2023 and written by Dennis Vaendel. Jori de Ruiter also gave me some textual advice.

The question: Do small bubbles influence the taste of the Cava Brut?

Have you ever wondered why the bubbles rise in a more or less straight line in some fizzy drinks and move much more chaotically in others? French and American physicists have figured out why. It simply has to do with the properties of the drink.

In a glass of Cava, the bubbles rise elegantly and neatly in a straight line. In a glass of beer or soft drink, the situation is usually less tidy and the gas bubbles shoot in all directions. It simply has to do with the properties of the drink. If you want to know how, simply read on…..

The answer:

French and American physicists figured it out. The results of their experiment, which were published in the journal 'Physical Review Fluids' the week before May 11, indicate that the behavior of the carbon dioxide bubbles mainly depends on the drink. The scientists discovered that the size of the bubbles and the presence of so-called surfactants, substances that influence the surface tension of a liquid, determine how the bubbles move through a drink. "Surfactants are the protein molecules in drinks that give them flavor and individuality and also ensure that the bubble chains remain stable," says one of the scientists of the study Roberto Zenit of Brown University in Providence, Rhode Island, US.

Influence of taste

The scientists discovered this by experimenting with different drinks, such as sparkling water, beer and champagne, in the lab. By pumping larger bubbles into the liquid or adding surfactants, a chaotic, 'unstable' chain of bubbles can be turned into a 'stable' straight bubble train.

High quality Cava = very small bubbles

In a sparkling wine with a high concentration of flavoring surfactants, such as a good Cava, the small bubbles ensure an elegant and neat straight line upwards. The carbon dioxide does not dominate and the drink 'rolls' very pleasantly in your mouth.

The size of the bubbles therefore appears to influence the quality. The researchers succeeded in making stable bubble chains in beer and water, which are normally reserved for champagne and similar drinks.

The shape of the bubble is decisive

The explanation for the behavior of the bubbles was found in the 'wake' of the bubbles. This is the turbulent area behind the gas bubble, which moves through the liquid and is comparable to the slipstream of a car. The experiment and additional computer simulations show that in liquids with little or no surfactants, the wake of the gas bubbles has a 'zigzag pattern'. This causes vortices, which push the pursuing bubbles aside and disrupt the bubble chain. "The bubbles move up more like a cone, rather than in a straight line," Zenit explains.

The surfactants, which reduce the tension between the liquid and the gas, on the other hand, create bubbles with a wake that 'sucks' other bubbles along in their path. For this, the bubbles follow each other neatly and the bubble chain remains stable.

More than a fun fact

The size of the bubbles appears to have a similar influence on their wake. Where small bubbles often show a zigzag pattern in beer and soft drinks, the wake of large bubbles has a suction effect. However, a straight line can also be seen in the liquids with many surfactants and smaller bubbles. For beer, in which the size of the carbon dioxide gas bubbles and the amount of surfactants can differ per brew, this produces different end results. As a result, one beer does contain straight bubble chains and the other does not.

According to the researchers, the new insights provide more than just a fun fact to tell over a drink. For example, it can help improve techniques for mixing gases with liquids in some water treatment plants. “Our master plan, by focusing on champagne and beer, is to make people understand that fluid mechanics is important in their daily lives,” said Zenit.

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