How many bubbles does a beer make?

A study provides quantitative information on bubbling in beer. (Image: LoveTheWind / iStock)

It should be sparkling: Tiny carbon dioxide bubbles make beer refreshing and ensure the development of the aroma. When looking at a freshly poured glass, one can ask oneself: How many of the bubbling tiny creatures are there? A study now provides at least a rough estimate of the magnitude. If you gently fill 250 milliliters of lager beer from a bottle into a glass, up to two million bubbles can then form until the glass is finally “stale”. However, since various factors play a role in the formation of bubbles, it can also be considerably fewer.

It hisses when it is opened and a foaming sound is heard when it is poured. It is well known that carbon dioxide dissolved in beer is responsible for these effects. It is created during fermentation through the activity of the yeasts. Similar to sparkling wines, the bubbles form important sensory elements for beer enjoyment, because they transport flavors and fragrances and give the drink a “sparkling kick”. In an earlier study, the researchers working with Gérard Liger-Belair from the Université de Reims Champagne-Ardenne calculated that around one million bubbles form in 100 milliliters of champagne. In their current study, they have now also devoted themselves to a quantitative assessment of the bubbling in a beer glass.

The bubbling in view

You focus on lager beer. As they explain, the amount of bubbles depends on several variables, so there can be a significant range. Above all, the carbon dioxide concentration in the beer is decisive, but other factors also play a role. As an example of a typical beer, the researchers used a commercially available product in 250 milliliter bottles with a content of 5.5 grams of dissolved carbon dioxide per liter. For the tests, the drink was poured gently into typical beer glasses at a temperature of six degrees Celsius, with a liquid level of 8.9 centimeters.

During the investigations, the researchers recorded the dynamics of the formation of bubbles that form on particles and tiny structures of the glass. As they explain, the bubbles increase in volume as they rise to the surface as they trap additional dissolved gas in the process. When the remaining gas concentration then decreases, the bubbling will eventually stop. The beer then reaches a state that is commonly referred to as stale or stale.

On the basis of observations of the formation of bubbles as well as theoretical calculations on the equilibrium of dissolved and gaseous carbon dioxide, the researchers finally came up with a range of bubble quantities that appears possible in their example: between 200,000 and two million bubbles could be released in the 250 milliliters of beer, emerges from the results.

Source: American Chemical Society

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