Beer lovers know this, the texture of the foam is an essential factor. Visually first, but also during tasting, because it influences both the aroma and the feeling in the mouth. A team of Swiss researchers spent seven years studying the stability of mosses of various Belgian beers by comparing each time the different degrees of fermentation in the brewing process. The results are rich in lessons for hop amateurs and lovers.
According to an online media article Ars Technicathe results show that the more the fermentation, the more the foam is stable. Everything would rest in the composition of proteins that play a key role in this sustainability. The fermented beers three times thus produce the most durable foams, while those of the unique fermentation lagers produce fine, more ephemeral foams.
The secret of fermentation
“The idea was to study directly what is happening in the liquid film which separates two bubbles”explains Emmanouil Chatzigiannakis, co-author of the study and university researcher at the Federal Polytechnic School of Zurich (ETH). The quantity of protein of simple fermentation lagers beers is not enough to stabilize the bubbles of the drink, which tends to promote a rapid collapse of the foam.
Conversely, those of triple fermentation beers form a protective network around bubbles which acts as a real safety net and maintains the foam longer, thus offering a richer and pleasant tasting experience. And if you really want to know everything, it is the lipid transfer protein that turns out to be decisive in the beer brewing process.
In single fermentation beers, it remains in a basic form, which is not enough to ensure lasting stability, but over the fermentation, it changes. During a double fermentation, this protein begins to assemble in more solid structures, then, during a triple fermentation, it fragments by creating both hydrophilic and hydrophobic parts, which allows it to stabilize the bubbles.
In other words, it acts as a natural surfactant, strengthening the walls of bubbles and making the foam much more resistant. If this discovery could inspire industrial applications to create more stable foams or improve milk foam, for the consumer the rule is simple: the more the fermentation is pushed, the more generous the foam, and each sip is savored to the last bubble – with moderation, of course.
