Compound
Lactones
Cyclic esters that give peach and apricot character, formed from fatty acids and often carried in bound form, which is why stone-fruit notes can appear in a cider months after fermentation.
Also called gamma-decalactone, Fruit lactones.
- Class
- Esters
- Formula
- Not a single molecule — see below
- How often it matters
- Specialist — met in particular circumstances
What it does in cider
- Are formed as internal esters when hydroxy fatty acids cyclise, either in the fruit or through yeast metabolism.
- Contribute peach, apricot and coconut aromas at low concentration, distinct from the apple and pear notes of the esters proper.
- Exist partly as open-chain hydroxy acids in equilibrium with the closed ring, with the position of the equilibrium set by pH — so a low-pH cider carries more of the aromatic closed form.
- Increase with maturation as bound and open-chain precursors slowly convert.
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.
- peach
- apricot
- coconut
- creamy stone fruit
Potent at low concentrations, and more perceptible in a low-pH cider because acidity shifts the equilibrium towards the volatile ring-closed form.
Descriptors it is responsible for
Sensory records that name Lactones as a cause. Each states the perception and the mechanism behind it.
- Hay — A dry, sweet-grassy note from coumarin and degraded green-leaf volatiles, characteristic of traditional farmhouse cider.
- Sherry — A nutty, oxidised, faintly volatile character from acetaldehyde and sotolon in long-air-exposed cider.
- Apricot — A concentrated, faintly honeyed stone-fruit note from lactones at higher concentration, common in ice cider and sweet styles.
- Dried fruit — Raisin and sultana character from long oxidative ageing, most often met in concentrated and fortified styles.
- Peach — A soft, sweet stone-fruit aroma produced by γ- and δ-lactones formed during fermentation and maturation.
- Quince — A dense, perfumed pome-fruit aroma sitting between apple and pear, driven by ethyl esters and terpene traces.
- Tinned pear — The syrupy, slightly flat pear character of canned fruit, from heat-degraded pear esters over residual sweetness.
- Cooked pear — Soft, sweet, heat-treated pear character, with the decadienoate top note stripped and a lactone-like weight left behind.
- Dried apricot — Concentrated stone fruit with an oxidative edge, from lactones developing alongside acetaldehyde and phenolic oxidation.
- 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. |
| Body | How much weight and viscosity the drink has in the mouth. |
| 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.
Bottle maturation
What happens to a cider after it is sealed in glass — which for most ciders is slow decline rather than improvement, and saying so is more useful than implying otherwise.
Tank maturation
Resting cider in stainless steel or a lined vessel, where the point of the container is that it contributes nothing and admits almost no oxygen.
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.
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.
Torulaspora delbrueckii
A non-Saccharomyces yeast that ferments further than most of its early-succession neighbours while producing notably little acetic acid.
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 Lactones
A lactone is an ester where the acid and the alcohol are parts of the same molecule, so the ester bond closes a ring. The ones that matter for aroma are formed from hydroxy fatty acids, and they smell of stone fruit — gamma-decalactone is the classic peach compound, and its relatives give apricot and a creamy coconut note.
Their behaviour in a cider is unusual in one respect. The closed ring is in equilibrium with the open hydroxy acid, which has no aroma, and the equilibrium is pH-dependent: acidic conditions favour the ring. A cider therefore carries a reservoir of potential aroma that is realised to a degree set by its own acidity, and a sharp cider will smell more of stone fruit than a low-acid one carrying the same total quantity.
They are also slow. Conversion from precursors continues through maturation, so a stone-fruit character that was not evident at bottling can be clear a year later — one of the few aroma changes in a maturing cider that runs upwards while everything else is fading. They should be kept distinct from the oak lactones, which are a different set of compounds arriving from wood rather than from fruit or ferment.
Related compounds
Compounds it is formed from, converted into, confused with, or routinely met alongside.
Esters
Oak lactones
The coconut-and-wood compounds of oak, whose concentration depends more on which species of oak the barrel was made from than on anything a cidermaker does.
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.
Phenolics
Terpenes
The floral and citrus aroma compounds that apples carry only in traces and that hops, spices and botanicals bring in quantity, which is why a hopped cider smells so different from an unhopped one.
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.
- 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.
- Does cider get better with age — Some does. Tannic, dry, bottle-conditioned ciders and ice ciders can gain for several years. Light, fruit-driven and commercially filtered ciders lose their aroma and do not gain anything in exchange.
- 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.
- How is cider matured
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.