Fault
Poor head retention
Foam that collapses immediately — most often caused by grease or detergent residue in the glass rather than by the beer.
Also called no head, flat-looking.
What it looks like
On pouring
Both a sound beer and a faulty one look the same at this point. The head is made by the pour, and everything that follows is about whether it is held.
After a minute
A sound head has lost a little depth and gained structure. This one has collapsed to a rim, which points at the glass before it points at the beer: fat and detergent both destroy foam at concentrations too low to see.
After three minutes
Nothing left and no lacing on the sides. Lacing is the diagnostic detail worth looking for — a beer that leaves rings as it goes down had a head worth having, whatever is on top of it now.
What it tastes and smells like
Head is stabilised by proteins and hop-derived iso-alpha acids, and destroyed by lipids. That is why the most common cause is not the beer at all: a trace of fat from food, lip balm, or detergent film in a glass will flatten the head of a perfectly good beer.
Styles this tends to affect
Not where it belongs — where it is most likely to appear when something has gone wrong.
- Oatmeal stout — A stout brewed with oats for a silky, full mouthfeel, balancing roast against smoothness rather than sweetness.
- Roggenbier — A German rye beer, spicy and full-bodied, fermented with Weissbier yeast for banana and clove alongside rye’s pepper.
If you are drinking it
If a beer will not hold a head, suspect the glass before the beer. Rinse it and pour again. If the head collapses in a clean glass across several beers, it is the beer.
Not a safety issue. Beer’s alcohol, hop compounds and low pH make it inhospitable to organisms that cause illness.
What causes it
| Cause | Stage | How often | Who can act |
|---|---|---|---|
| Grease, detergent residue or fat in the glass. A "beer-clean" glass is one where water sheets evenly rather than beading. | dispense | most common | venue |
| Insufficient foam-positive protein, typically from a very high proportion of sugar or unmalted adjunct. | mashing | common | brewer |
| Lipid carry-over from grain, or from adjuncts such as cocoa butter or nut oils. | mashing | occasional | brewer |
If you are brewing it
- Venue: Wash glasses with a dedicated glass detergent, rinse thoroughly, and air-dry rather than towel-drying. (prevents)
- Brewer: Include wheat, torrified wheat, flaked barley or a dextrin malt for foam-positive protein. (prevents)
Where in the process this comes from
Steps that can produce this fault when they go wrong. Each links to what the step is for and how it is controlled.
- Filtration — Pass beer through a filter medium to remove yeast and haze-forming particles, producing bright beer with a long, stable shelf life.
Evidence
What BeerHQ knows about this, and how. Every statement carries the state of the evidence behind it rather than being presented flatly as fact.
Beer foam is stabilised by specific barley proteins that survive the brew — the lipid transfer proteins and the serpins, protein Z among them — rather than by carbonation alone.
Checked against the source
Source: Kerr et al., "Posttranslational Modifications Drive Protein Stability to Control the Dynamic Beer Brewing Proteome" (2019), results, foam-associated proteins (Mol Cell Proteomics 18(9):1721–1731)