WASHINGTON, August 26, 2025 – Beer, a beloved beverage worldwide, is often judged by the frothy foam crowning a freshly poured glass. This foam is not just a visual delight; it serves as a marker of a beer’s quality and the completion of its fermentation process. Despite its significance, the science behind a stable beer foam remains a mystery.
Researchers from ETH Zurich and Eindhoven University of Technology have embarked on a journey to decode this enigma. Their study, published in Physics of Fluids by AIP Publishing, delves into the stability of beer foams, examining various beer types at different fermentation stages.
The Science Behind Beer Foam
Beer foam, much like any other foam, consists of numerous small air bubbles separated by thin liquid films. The stability of these films is crucial; if they fail, the bubbles burst, causing the foam to collapse. The factors contributing to the stability of these films might include protein conglomerates, surface viscosity, or surfactants, which are known to reduce surface tension and are commonly found in soaps and detergents.
According to Emmanouil Chatzigiannakis, one of the study’s authors, beer presents an ideal medium for foam research. “The idea was to directly study what happens in the thin film that separates two neighboring bubbles,” he explained. “And the first thing that comes to mind when thinking of bubbles and foams is beer.”
Innovative Research Techniques
The research team employed a combination of scientific imaging and rheometry techniques to observe how these thin films maintain their integrity to form a stable foam. “We can directly visualize what’s happening when two bubbles come into close proximity,” said Chatzigiannakis. “We can directly see the bubble’s protein aggregates, their interface, and their structure.”
The study revealed that in single fermentation beers, the foam’s stability is primarily due to the beer’s surface viscosity. In contrast, double-fermented beers exhibit a different mechanism. Here, proteins form a two-dimensional structure, imparting an elastic quality to the thin films, thereby prolonging their stability.
Broader Implications and Future Research
This discovery highlights beer as an excellent model for studying foam stability with potential applications beyond brewing. The research could impact fields ranging from oil separation to firefighting chemicals and even medical treatments like varicose vein therapy.
“This is an inspiration for other types of materials design, where we can start thinking about the most material-efficient ways [of creating stable foams],” said Jan Vermant, another author of the study. “If we can’t use classical surfactants, can we mimic the 2D networks that double-fermented beers have?”
The researchers hope their findings will resonate with the brewing industry, inspiring innovations in foam management. Future studies may focus on techniques to modulate foam quantity, ensuring that every beer enthusiast can enjoy the perfect pour.
As the science of beer foam continues to unfold, it not only enhances our understanding of this popular beverage but also opens doors to new technological advancements across various industries.
