Researchers in Japan have cracked the code behind the iconic bubble cascade formation in a glass of Guinness beer – a feat that was “previously impossible to explain.” 

Understanding bubble formation based on certain conditions is expected to lead to improvements in quality control for fermented foods and wastewater treatment.

Kirin Holdings Institute for Future Beverages conducted the joint research with a research group from the Fluids Engineering Research Group of the Graduate School of Engineering Science at Osaka University. Their results were recently published in the US’ Physical Review E scientific journal. 

A mysterious flow
In previous joint research at Osaka University, it was found that the bubbles in Guinness Draught form a “rolling wave” pattern as bands of liquid roll down the inclined surface of the glass.

But the cascading pattern only occurs under certain conditions. Carbonated water, cola, and other non-stout beers do not exhibit similar patterns – they flow upwards. 

The bubbles in Guinness beer are made of nitrogen gas and are about one-tenth the size of the bubbles in carbonated beverages and rise slowly. 

Because a large volume of bubbles remain in the beer for a long period of time, the beer has a creamy flavor, and it also leads to a unique pattern created from collective bubble flows. 

However, a scientific explanation governing the formation of this bubble pattern remained elusive, and it was viewed to be a peculiar phenomenon.

Previous studies were limited in that they were not able to control the volume or size of the bubbles. 

The mathematical model 
The most recent research used a supercomputer to conduct a simulation of bubble flow. By discovering a mathematical model for the formation of the bubble cascade, it was revealed that the pattern forms under certain conditions.

These conditions include stability or instability and the density or sparsity of the bubbles. By creating a mathematical model, it is now possible to predict the occurrence of this phenomenon based on the shape of the cup.

Furthermore, the research found that the pattern can appear if relatively dense conditions are created when pouring carbonated water or cola into an extremely large container such as a 200-liter drum, as opposed to a small glass.

Researchers believe this mathematical formula will have applications in the quality control of fermented foods. 

The fermented trend
The age-old process of fermenting food is still innovating, as FoodIngredientsFirst spoke to suppliers this March on next-generation fermented ingredients. 

Fermentation has also been spotlighted as a “crucial pillar for alternative proteins,” with players such as Perfect Day utilizing the technology to propagate proteins for dairy alternatives. 

Fermented foods are also renowned for their naturally occurring probiotics, which may support intestinal flora and better overall health.