Compound
Ethyl acetate
The most abundant ester in cider, giving lift and pear-drop at low concentration and nail varnish at high, and the earliest audible warning that acetic bacteria are at work.
Also called Acetic ester.
- Class
- Esters
- Formula
- C4H8O2
- How often it matters
- Central to how cider behaves
What it does in cider
- Forms both from yeast during fermentation and from acetic acid bacteria afterwards, so its presence means different things at different stages.
- Contributes fruity lift and a pear-drop note in trace, and solvent harshness above roughly 150 mg/L in cider.
- Announces acetification well before acetic acid itself becomes obvious, because it is detected at a far lower concentration than the acid.
- Increases the perceived harshness of volatile acidity, so a cider with both reads as worse than either figure alone would predict.
How it is perceived
What the compound registers as, and at roughly what concentration. Perception is not a property of the molecule alone: sugar, tannin and carbonation all change where a threshold falls.
- pear drop
- nail varnish
- solvent
- glue
- lifted fruit
Commonly described in cider as contributing positively up to somewhere around 150 mg/L and as a clear fault above it, though the boundary depends heavily on the cider: sugar and tannin both mask it, and a delicate cider shows it far earlier than a robust one.
Descriptors it is responsible for
Sensory records that name Ethyl acetate as a cause. Each states the perception and the mechanism behind it.
- Nail varnish — The sharp solvent lift of ethyl acetate above threshold, the commonest volatile fault-adjacent note in cider.
- Pear drop — The sweet-shop confectionery note of isoamyl acetate with ethyl acetate behind it — a fermentation product, not a pear one.
- Vinegar — Acetic acid from acetic acid bacteria oxidising ethanol in the presence of air — the classic cider spoilage.
- Glue — Ethyl acetate at fault concentration, past the solvent stage and into adhesive.
- Solvent — A general chemical, thinner-like impression from ethyl acetate and higher alcohols together.
- Apple pomace — The wet, sweet-sour smell of freshly milled and pressed pomace: cut-apple aldehydes over the first traces of wild fermentation and browning.
- Cider shop — The characteristic smell of a working cider house — ferment, wood, fruit and a trace of acetic lift together.
- Acetone — A harsher, more chemical solvent note than ethyl acetate alone, from ketones alongside high volatile esters.
- Fermenting vat — The pungent, CO2-lifted smell of a ferment in full activity, met in very young cider straight from the vessel.
- Fruit store — The close, sweet, faintly fermenting smell of a loft of apples held before milling, met in ciders made from sweated fruit.
The structure it moves
| Dimension | What it is |
|---|---|
| Fermentation character | Aromas made by the ferment rather than carried in from the fruit. |
| Fruit character | How strongly the drink smells of apple or pear, and of fruit generally. |
| Freshness | Whether the drink smells and tastes of live fruit or of time and air. |
Measured figures
Shown as they were measured, with the context each was taken in. They are not averaged: a concentration recorded in one country's fruit in one decade is not a constant.
Ethyl acetate24.0–50.0 mg/L
Villaviciosa, Asturias, Spain, 2001–2002 · 4 samples · Gas chromatography with flame ionisation detection · Suárez Valles, Pando Bedriñana, Fernández Tascón, Querol Simón and Rodríguez Madrera, Food Microbiology 24(1):25–31
Spontaneously fermented cider with no sulphite and no fault. The authors read the result through the ratio rather than the concentration: ethyl acetate to higher alcohols stayed below 0.3 in every cider, which is what a clean ferment looks like. The same compound at several hundred milligrams per litre is the solvent fault.
The commonest ester in cider, pear-drop at low concentration and solvent at high, and the compound whose ratio to the higher alcohols tells a maker how clean the ferment was. Measured in milligrams per litre.
What forms it
Processes that put this compound into the drink, or increase how much of it is there.
Wild fermentation
Letting the microflora already present on the fruit and in the press house carry the ferment, in a succession rather than as a single organism.
Inoculated fermentation
Starting a ferment by pitching a chosen yeast culture so that one known strain, rather than the fruit’s resident population, does the work.
Oxidative maturation
Ageing a cider with a deliberate, measured oxygen supply so that tannins polymerise and soften and an aldehydic character develops on purpose, which is not the same thing as the oxidation fault.
Barrel ageing
Holding cider in wood — which may mean an old neutral vat used simply as a vessel, or fresh or spirit-seasoned oak used as a source of flavour, and the two are not the same operation.
What removes or limits it
Processes that reduce it, hold it below a threshold, or stop it forming in the first place.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
Topping up
Refilling a maturing vessel as evaporation and racking losses lower the level, so that no significant surface of cider is ever left in contact with air.
Blending
Combining separate lots of cider or perry into one, which in cider is the historically normal way of making the drink rather than a remedy applied when single lots disappoint.
Faults it is implicated in
Being implicated is not the same as being a fault. Several of the compounds on this site are ordinary constituents of a sound cider and define a named fault only above a concentration.
Ethyl acetate taint
A solvent, nail-varnish or pear-drop aroma from ethyl acetate, the most abundant ester in cider and the one that turns from lift to fault over a narrow range.
Volatile acidity
The measurable fraction of acidity that can be steam-distilled off, dominated by acetic acid and read as vinegar sharpness in the nose and a hard, hot finish.
Acetification
The active conversion of a cider’s ethanol into acetic acid by acetic acid bacteria at an air interface — the process, running in the vessel, that produces volatile acidity.
Film yeast growth
A pale, powdery or wrinkled film of aerobic yeast growing on the surface of a standing cider, consuming alcohol and acid and producing acetaldehyde.
Vinegar fly contamination
Small flies carrying acetic acid bacteria and spoilage yeasts directly into juice and cider, and depositing them wherever they land.
Organisms that produce it
Which organism is responsible usually decides whether the compound is a feature or a symptom.
Acetobacter aceti
An acetic acid bacterium that oxidises ethanol to acetic acid wherever cider meets air, and the organism behind most volatile acidity in cider.
Gluconobacter oxydans
A sugar-preferring acetic acid bacterium abundant on damaged fruit and in fresh juice, which oxidises glucose to gluconic acid before fermentation begins.
Hanseniaspora uvarum
The apiculate yeast most often reported from grapes and widely present on apples too, whose anamorph name *Kloeckera apiculata* still appears throughout older cider literature.
Kloeckera apiculata
The anamorph name for *Hanseniaspora uvarum*, still in wide use in cider writing, and often used loosely as a collective term for all apiculate yeasts.
Pichia membranifaciens
A film-forming yeast that grows as a skin on the surface of cider left in contact with air, consuming ethanol and acid and leaving the cider thin.
About Ethyl acetate
Ethyl acetate is acetic acid joined to ethanol, and in cider it comes from two sources that a taster cannot distinguish but a maker must. During fermentation, yeast makes it — and the apiculate yeasts that dominate the first days of a spontaneous ferment, Hanseniaspora and Kloeckera, make a great deal more of it than Saccharomyces does. This is why wild ferments so often carry a pear-drop or solvent note that inoculated ferments lack, and why that note is present from the beginning rather than developing later.
After fermentation the source changes. Acetic acid bacteria growing at an exposed surface make both acetic acid and its ethyl ester, and because the ester is perceptible at a small fraction of the acid’s concentration, it is what a taster meets first. A cider that smells faintly of glue is telling its maker that air is reaching it, several weeks before the volatile acidity figure will look alarming.
The compound is not a fault by nature. At low concentration it lifts fruit aroma and is part of the normal ester complement of any fermented drink. What makes it problematic is that its two sources point in opposite directions: as a yeast product early it is a stylistic feature, and as a bacterial product late it is a symptom. Reading it correctly means knowing when it appeared, which is one of the practical arguments for tasting a cider regularly through maturation rather than only at bottling.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Acids
Acetic acid
The vinegar acid, made by bacteria oxidising ethanol whenever air reaches a cider, and the one fault in cider that no later processing can undo.
Alcohols
Ethanol
The alcohol yeast makes from fruit sugar, which converts a perishable juice into a keepable drink and carries most of its aroma to the nose.
Esters
Isoamyl acetate
The banana and pear-drop ester, made by yeast from isoamyl alcohol, and one of the clearest chemical signatures of a warm fermentation.
Aldehydes
Acetaldehyde
The compound sitting one step short of ethanol, which smells of bruised apple and sherry, binds most of the sulphite added to a cider, and is the chemical signature of oxidation.
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- How many calories are in cider — Roughly 40 to 60 kcal per 100 ml for most ciders, so a UK pint falls somewhere around 200 to 250 kcal. Alcohol contributes about 7 kcal per gram and residual sugar about 4, so both strength and sweetness matter.
- Why does my cider taste like vinegar — Acetic acid bacteria have reached the cider and, given air, are converting its alcohol into acetic acid. The cause is almost always oxygen — an unfilled vessel, a leaking bung, or a slow transfer.
- Can you fix a cider that has gone vinegary — Not really. Volatile acidity cannot be removed at small scale, and blending it away only dilutes it. The realistic options are to accept it, to blend a lightly affected batch into a much larger sound one, or to let it finish becoming vinegar.
- How much acetic acid is normal in cider — A small amount is present in every cider and contributes lift. Sound Asturian sidra natural has been measured at 0.2 to 0.3 g/L, and a clean modern cider much above about 0.7 g/L is generally showing a fault rather than a style.
- Why does my cider smell like nail varnish — That is ethyl acetate, formed when acetic acid combines with ethanol. In small amounts it reads as pear drops; above threshold it smells of solvent or nail varnish remover and usually accompanies rising volatile acidity.
- How does cider ferment — Yeast consumes the sugar in apple juice and produces roughly equal masses of ethanol and carbon dioxide, along with the esters and higher alcohols that give cider much of its aroma. In a wild ferment several yeast species take turns before *Saccharomyces* finishes the job.
Where to go next
- All compounds — Grouped by what the fruit brings and what the ferment makes of it.
- Sensory — Every descriptor, with the compound or process that causes it.
- Microbiology — The organisms whose metabolism most of this chemistry belongs to.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
The Science of Cidermaking and associated technical writing
Andrew Lea · reference work · passage verified 2026-08-24
Written by a food chemist who worked at Long Ashton on apple phenolics. Unusual among specialist cider writing in that it is primary-research-adjacent: the author is describing work he did, and cites the literature. This is why it is registered at tier 1 for chemistry while a general cider book is not.
Peer-reviewed literature on cider fermentation microbiology
Various journals · peer-reviewed literature · registered as competent for this subject
Covers the microbial succession of spontaneous cider fermentation, the role of non-Saccharomyces yeasts in the early stages, malolactic conversion by Oenococcus and Lactobacillus species, and the organisms behind the principal spoilage faults.
Cider and perry production technical training material
Peter Mitchell / Cider and Perry Academy · reference work · registered as competent for this subject
Searched again on 2026-08-25 and it remains the one printed source here that a bibliographic check cannot fix, because it is not a published work with an edition. It is course material issued to participants of a training programme, so there is no catalogue record to verify, no ISBN, and no lawful public copy. Its state stays `registered` for that reason rather than through inattention.