Fault
Solvent
A solvent-like ester that reads as pear drop at low levels and as nail varnish remover at high ones.
Also called ethyl acetate, nail varnish, acetone.
What it tastes and smells like
Responsible compound: ethyl acetate.
Where it may be expected
A low level of ethyl acetate contributes a pleasant pear-drop or light fruit note in strong Belgian and wheat styles, where it is part of the ester complexity a warm fermentation is meant to produce. Nail-varnish intensity is a fault everywhere.
Intensity and context decide. In the styles below a restrained version of this can be part of the character; the same character running past that is still a fault there.
Styles this tends to affect
Not where it belongs — where it is most likely to appear when something has gone wrong.
- Belgian blond ale — A moderately strong golden Belgian ale, soft and lightly sweet, with gentle yeast fruit and spice and a dry finish.
- Belgian dark strong ale — The strongest of the Belgian dark ales: raisin, fig and dark caramel over substantial warmth, with a surprisingly dry finish.
- Belgian golden strong ale — Pale, very dry and highly carbonated, with intense pepper and fruit and a strength its lightness completely conceals.
- Belgian IPA — American hop intensity fermented with expressive Belgian yeast, producing pepper and fruit alongside citrus and pine.
- Belgian pale ale — An everyday Belgian ale, toasty and biscuity, with restrained yeast character compared with the stronger Belgian styles.
- Belgian single — The low-strength pale beer brewed for the monastery’s own table, dry and hoppy with full Belgian yeast character.
- Bière de Garde — A malty, rounded French farmhouse ale brewed for keeping — richer and less peppery than its Belgian saison cousin.
- Dubbel — A dark Belgian ale rich in raisin, plum and caramel from dark candi sugar, dry-finishing despite its sweetness of flavour.
- Eisbock — A doppelbock concentrated by partially freezing it and removing the ice, intensifying malt, body and alcohol together.
- English barley wine — The strongest traditional English ale: dense malt, dried fruit and marmalade, built to be kept for years.
- Imperial stout — The strongest stout: dense, viscous and intensely roasted, with dark fruit, chocolate and substantial alcohol warmth.
- Tripel — A strong pale Belgian ale that is simultaneously rich and dry, with pepper, orchard fruit and a sparkling, deceptive drinkability.
If you are drinking it
A sharp nail-varnish note means a hot or stressed fermentation. Harmless but not what the brewer intended.
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 |
|---|---|---|---|
| High fermentation temperature or stressed yeast producing excessive ethyl acetate. | fermentation | most common | brewer |
| Acetic acid bacteria producing ethyl acetate alongside acetic acid where oxygen is present. | conditioning | occasional | brewer |
If you are brewing it
- Brewer: Control fermentation temperature and pitch adequate healthy yeast. (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.
- Top fermentation — Ferment warm with Saccharomyces cerevisiae, producing the ester and phenol character that distinguishes ales from lagers.
Often confused with
- Fusel alcohol — solvent, nail varnish
- Acetic acid — vinegar, sharp acidity
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.
Acetate esters — ethyl acetate among them — are made by the yeast rather than extracted from anything. Acetyltransferase enzymes join acetyl coenzyme A to an alcohol, so the ester a beer carries depends on which alcohols the fermentation produced.
Checked against the source
Source: Lilly et al., "Effect of Increased Yeast Alcohol Acetyltransferase Activity on Flavor Profiles of Wine and Distillates" (2000), abstract and introduction (Appl Environ Microbiol 66(2):744–753)
Raising fermentation temperature or wort gravity increases acetate ester production, which is why the same yeast gives a clean beer in a cool fermentation and a solvent-like one when it runs hot.
Checked against the source
Source: Svedlund et al., "Fruits of their labour: biotransformation reactions of yeasts during brewery fermentation" (2022), section on acetylation of 3-mercaptohexanol (Appl Microbiol Biotechnol 106(13–16):4929–4944)