Breakthrough in Beer Brewing: Stable Foam Formula Uncovered

Researchers at ETH Zurich, led by Professor Jan Vermant, have uncovered significant insights into the stability of beer foam through a seven-year investigation published in the journal Physics of Fluids.

This study began with a question from a Belgian brewer about controlling brewing by observing foam. Their findings reveal that the foam stability of different beer styles is influenced by complex interactions between proteins and surface forces.

The team analyzed various Belgian ales, discovering that 'Tripel' beers produced the most stable foam, followed by 'Dubbel' and 'Singel' beers, with the latter losing foam quickly due to lower alcohol content and milder fermentation.

In addition to these ales, the team evaluated two Swiss lagers, noting significant differences in their foam stability. Historically, it was believed that proteins in beer created a protective layer around bubbles, but this work shows foam stability is more nuanced.

For lagers, stability is tied to surface viscoelasticity, which is affected by protein levels and how these proteins denature. 'Tripel' beers, however, rely on Marangoni stresses, which are forces that arise from surface tension variations across the liquid.

This effect can be likened to crushed tea leaves on water that react when soap is introduced, creating swirling currents that stabilize foam. The research also highlights how the protein-rich shells surrounding bubbles behave differently in various beer types.

In 'Singel' beers, these shells resemble tightly packed, small spherical particles, while 'Dubbel' beers have a mesh-like structure for added strength. 'Tripel' beers exhibit bubble dynamics similar to surfactants.

The researchers identified the lipid transfer protein 1, or LTP1, as a crucial component in foam stability. Vermant has emphasized that improving foam stability requires a careful approach, as changing one parameter can adversely affect others.

The team is collaborating with a major brewery to apply these findings to enhance foam quality. Beyond brewing, the implications of this research extend to various industries, including electric vehicles, where foaming lubricants can pose risks.

The team is working with Shell to address foam breakdown, and they are also exploring environmentally friendly surfactants. Their findings may also inform food science, particularly in stabilizing milk foam, as they collaborate with ETH Zurich food researcher Peter Fischer.

Vermant concludes that the knowledge gained from beer brewing has broad applications and could lead to significant advancements across multiple fields.