The “Guinness Cascade” is the name given to a phenomenon that you can observe if you are served a Guinness press in an irish pub. When you are served a pint of this famous stout, the gas bubbles seem to sink to the bottom of the glass, creating the impression of a fall, and different layers of brown and white colours in your pint . A rather nice chemical reaction to see, which contributes to the pleasure of the consumer before sipping his pint… Here is a small explanation of this phenomenon, called “Guinness Cascade”.
No, the Guinness Cascade is not an optical illusion as some might think: this reaction would be a natural phenomenon, created by the temperature difference between the beer being poured and the glass. Generally, Guinness is served chilled, at a temperature of 6°C, by means of a special nitrogen filler. Nitrogen generates smaller bubbles than carbon dioxide (which is used in more traditional filler machines), which gives Guinness its distinctive fizz.
However, using nitrogen requires a few rules to be followed. For example, the barman must fill the pint of Guinness twice before it can be served properly.
This step, coupled with the temperature difference between the glass and the beer would then create a convection current, forcing the gas to go up through a central current, then down on the periphery of the glass, creating this stratification effect.
It is then advisable to wait for this effect to subside before the Guinness can be drunk. According to the specialists, the beer would be better after this slight waiting time (more uniform, it would then have an ideal foam, where one could draw a clover without it disappearing).
This phenomenon often generates amusing discussions at the Pub! However, this phenomenon is not limited to Guinness. The Guinness Cascade can indeed occur with any liquid, but the contrast produced by a beer as black as Guinness and clear bubbles make the reaction all the more visible. A rather funny chemical reaction therefore, and which makes the signature of this exceptional beer!Alcohol abuse is dangerous for your health. Consume in moderation.