Compound
Ethyl butanoate
A short-chain ethyl ester perceived at very low concentration, giving the sweet pineapple-and-apple lift that reads as ripe fruit in a young cider.
Also called Ethyl butyrate.
- Class
- Esters
- Formula
- C6H12O2
- How often it matters
- Occasional
What it does in cider
- Is formed by yeast from butanoyl-CoA and ethanol during fermentation, by a different route from the acetate esters.
- Contributes sweet, ripe fruit aroma at concentrations in the low tens of micrograms per litre.
- Reinforces the perception of sweetness, so a dry cider carrying it reads as fruitier and less austere than its sugar figure suggests.
- Is comparatively stable in the bottle relative to the acetate esters, so it persists as fresher notes fade.
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.
- pineapple
- ripe apple
- sweet fruit
- bubblegum
One of the lower thresholds among cider esters, reported in the region of tens of micrograms per litre, so it contributes at concentrations that analysis barely registers.
Descriptors it is responsible for
Sensory records that name Ethyl butanoate as a cause. Each states the perception and the mechanism behind it.
- Ripe apple — Full orchard-apple aroma from the acetate esters an apple accumulates through ripening and carries into the finished drink.
- Dessert apple — The bright, aromatic, low-tannin fruit character of eating apples, dominant in eastern counties and most modern mainstream cider.
- Lemon — A sharp citrus impression built from high malic acid read alongside light esters and terpene traces.
- Overripe apple — Heavy, faintly alcoholic fruit aroma from apples past the climacteric, where the fruit has begun fermenting on its own account.
- Pineapple — Sharp, sweet tropical fruit from short-chain ethyl esters, chiefly ethyl butanoate and ethyl hexanoate.
- Strawberry — A soft red-fruit note from furanone and ester chemistry, arising in fermentation or from added fruit.
The structure it moves
| Dimension | What it is |
|---|---|
| Fruit character | How strongly the drink smells of apple or pear, and of fruit generally. |
| Fermentation character | Aromas made by the ferment rather than carried in from the fruit. |
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.
Yeast selection
Choosing which cultured strain to pitch, on the basis of the temperature, nitrogen, alcohol and aroma behaviour that separates one commercial yeast from another.
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.
Cooked character
A stewed-apple, caramel or jam-like character from heat applied to juice or cider, most often through pasteurisation or hot storage.
Flat and lifeless
A cider with nothing obviously wrong and nothing to say: aroma faded, acidity dulled, finish short — usually the cumulative result of over-processing or slow oxidation.
Organisms that produce it
Which organism is responsible usually decides whether the compound is a feature or a symptom.
Saccharomyces cerevisiae
The yeast that finishes essentially every cider, whether it arrives in a sachet or from the fruit, the press and the vessel.
Metschnikowia pulcherrima
An early-succession yeast that suppresses competitors by locking up iron, and is used commercially as a controlled non-Saccharomyces partner rather than as a fermenter.
About Ethyl butanoate
Ethyl esters of fatty acids are made by a different enzyme system from the acetate esters, using acyl-CoA intermediates from the yeast’s own fatty acid synthesis. Ethyl butanoate is the shortest of the group that matters in cider, and its aroma is a sweet, ripe, slightly confected fruit that panels describe as pineapple as often as apple.
Its importance is a threshold effect. It is perceptible at concentrations far below anything that would register on a routine analysis, so a cider can carry a clear ripe-fruit aroma from a compound present at a few parts per billion. This is the general reason aroma chemistry cannot be inferred from bulk composition.
It also affects taste and not only smell. Fruit esters read as sweetness to most drinkers, and a fully dry cider with a strong ester profile is routinely described as off-dry by people tasting it blind. This gap between measured and perceived sweetness is one of the most consistent findings in cider sensory work, and it is worth knowing before adjusting sugar in a blend.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Esters
Ethyl hexanoate
One of the most powerfully aromatic esters in cider, perceptible at a few micrograms per litre, contributing green apple and aniseed to the fruit complex.
Esters
Ethyl octanoate
A medium-chain ethyl ester contributing ripe pear and a waxy sweetness, and one of the compounds that makes an ester-forward cider feel rounder as well as fruitier.
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.
Esters
Hexyl acetate
The apple-skin and pear ester that is genuinely carried in from the fruit rather than made by the yeast, and one of the few fresh-fruit aromas that survives fermentation.
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.
- Which yeast ferments cider — Saccharomyces cerevisiae finishes almost every cider fermentation, whether it was pitched or arrived from the press house. In a spontaneous ferment it is not the first organism present, only the one that survives the alcohol it makes.
- 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.
- What yeast should i use for cider — CiderHQ does not recommend brands. The choice is between a neutral, reliable strain that lets the fruit show, an aromatic wine strain that adds its own esters, and no addition at all. Alcohol tolerance, cold tolerance and nitrogen demand are the properties worth comparing.
- Can you make cider from shop bought apple juice — Yes, provided the juice contains no preservative — check for potassium sorbate or benzoate on the label. Pasteurised juice ferments perfectly well once yeast is added, because pasteurisation removes the organisms but not the sugar.
- What are esters in cider — Esters are compounds formed when an acid and an alcohol combine, and they carry most of the fruity aroma in cider — banana, pear drop, apple, pineapple. Yeast makes them during fermentation, and warm ferments make more.
- What does metschnikowia do in a cider ferment — It locks iron out of solution as the red pigment pulcherrimin, which inhibits organisms that need iron. That is a defined antimicrobial mechanism rather than simple competition, and it is why the species is sold for sequential inoculation.
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.
Washington State University cider research programme
Washington State University Northwestern Washington Research and Extension Center · university · passage verified 2026-08-24
The single most useful open cider dataset CiderHQ has found. The programme’s cultivar performance database gives juice chemistry, orchard behaviour, bloom and harvest timing and cider-maker tasting notes for 73 cultivars grown at one maritime site over fifteen years, and — unusually — publishes its classification thresholds alongside its figures, so the classification can be checked rather than taken on trust. It also states outright that its results diverge from the English ones. Read in full on 2026-08-24 and transcribed into `data/trials/wsu-mount-vernon.ts`; four published figures were found to be impossible and are withheld there with their reasons.