‘Really rich physics going on’: the science behind a flat pint of lager

Research reveals why single fermentation beers sometimes lack the thick, stable foam of other pub favourites

A flat pint of beer with no head is a common gripe among pub-goers. And while the bar staff's pint-pulling technique is often assumed to be the cause, scientists have discovered that the stability of beer foam is also highly dependent on the chemical makeup of the brew.

Triple fermented beers have the most stable foams, the study found, while the froth created by single fermentation beers, including lagers, are inherently more likely to collapse before you have time to take the first sip.