Compound
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.
Also called Ethyl caproate.
- Class
- Esters
- Formula
- C8H16O2
- How often it matters
- Occasional
What it does in cider
- Is produced by yeast from hexanoyl-CoA, in proportion to the medium-chain fatty acids the ferment generates.
- Delivers apple and aniseed aroma at concentrations of a few micrograms per litre, among the lowest thresholds of any cider volatile.
- Rises in cool fermentations, where medium-chain fatty acid synthesis is favoured.
- Persists better than the acetate esters through the first years in bottle.
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.
- green apple
- aniseed
- fruit gum
- brandy
Among the lowest thresholds in the cider aroma set, reported in the low micrograms per litre.
Descriptors it is responsible for
Sensory records that name Ethyl hexanoate as a cause. Each states the perception and the mechanism behind it.
- 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.
- Quince — A dense, perfumed pome-fruit aroma sitting between apple and pear, driven by ethyl esters and terpene traces.
- Red fruit — A general soft red-berry impression from medium-chain ethyl esters, most often met in tannic ciders with some age.
- Strawberry — A soft red-fruit note from furanone and ester chemistry, arising in fermentation or from added fruit.
- Williams pear — The intense, perfumed pear character of Williams and Bartlett fruit, driven by decadienoate esters at high concentration.
- Mango — Soft, ripe tropical character from lactones and esters together, met in warm-climate and modern cultured ciders.
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.
Fermentation temperature control
Managing the temperature at which a ferment runs, which sets not only how fast it goes but which aromatics survive it and what the finished cider tastes of.
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.
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.
Saccharomyces uvarum
A cold-tolerant relative of *S. cerevisiae* recovered from spontaneous cider and wine ferments, associated with low-temperature fermentation and higher glycerol.
About Ethyl hexanoate
The ethyl esters of hexanoic, octanoic and decanoic acid form a family, made by the same enzyme system from the fatty acids a fermenting yeast produces. Ethyl hexanoate sits at the aromatic end of that family: its threshold is among the lowest of any compound in cider, and it contributes green apple and a distinct aniseed edge that trained panels pick out readily.
Because it depends on medium-chain fatty acid synthesis, it responds to the same conditions that favour that pathway. Cool fermentations produce more; so do ferments with limited oxygen, since oxygen diverts the yeast towards sterol synthesis instead. A cool anaerobic ferment is therefore estery in two different ways at once, through this family and through the acetates.
For anyone judging a cider, the family is worth separating from the acetates. Acetate esters read as confected — banana, pear drop, boiled sweet. These read as fruit — apple, pineapple, pear flesh. A cider dominated by one smells quite different from a cider dominated by the other, even though both would be described as estery.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Esters
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.
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
Ethyl decanoate
The longest of the common medium-chain esters, contributing waxy and faintly floral weight rather than obvious fruit, and prone to dropping out of solution in the cold.
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 temperature should cider ferment at — Most cider is fermented cool, commonly between about 12 and 18 °C. Cooler ferments keep more fruit aroma and run slower; above the low twenties the cider tends towards hot, solvent-like higher alcohols.
- 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.
- Which yeast ferments cider in the cold — Saccharomyces uvarum, a cold-tolerant relative of the ordinary wine and cider yeast. It is associated with slow low-temperature ferments and produces more glycerol and a different higher-alcohol profile than S. cerevisiae.
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.
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.