Fermentation
Arrested fermentation
Deliberately halting a ferment while sugar remains, to obtain natural sweetness from the fruit rather than from an addition — and accepting the instability that follows.
Also called Stopped fermentation, Halted ferment, Fermentation arrest.
- Stage
- Fermentation
- Traditional in
- Pays d’Auge, Normandy, Domfrontais
- What it most changes
- Sweetness up, alcohol down
- Safety
- Carries a safety consideration — see below
A cider arrested with sugar remaining is not a finished product until it has been genuinely stabilised or is being held cold throughout its life. Bottling one that still carries viable yeast risks the ferment resuming in the closed bottle, where the carbon dioxide has nowhere to go: pressure can rise to the point where glass fails or a closure is expelled. Before bottling an arrested cider, confirm by assay rather than by gravity that fermentable sugar and yeast are under control, and treat repeated stable gravity readings alone as insufficient evidence.
What it is
Arrested fermentation is the deliberate interruption of an active ferment at a chosen point, leaving some of the fruit’s original sugar unfermented in the finished drink. It is achieved by removing the yeast, by making conditions untenable for it, or both: chilling the vessel so the population becomes dormant and settles, racking the clear cider off the settled lees repeatedly, filtering the yeast out, adding sulphite, or a combination applied in sequence. What distinguishes it from a stuck fermentation is intent and control. What it shares with a stuck fermentation is the underlying condition — a liquid containing both fermentable sugar and, usually, some surviving yeast.
Why it is used
- It produces a genuinely sweet cider whose sweetness comes from the apples themselves, with the accompanying lower alcohol, rather than from sugar or juice added back after fermentation.
- Because the sugar left behind is the fruit’s own, the drink retains a fruit character and a sugar-acid relationship that back-sweetening a dry cider does not reproduce.
- Stopping the ferment before dryness preserves aromatic compounds that a full fermentation would strip with the escaping carbon dioxide.
- Partial arrest at a controlled point is how a maker reaches an intermediate sweetness — the demi-sec territory between dry and sweet — without blending two finished ciders.
How it works
- Chilling drops the yeast below the temperature at which it divides; the cells lose buoyancy as they cease fermenting and settle, so cold both stops metabolism and begins the physical separation.
- Successive rackings off the settled deposit progressively remove yeast cells and the nutrients they need, so each racking leaves a population smaller and hungrier than the one before — this is the traditional method and works by attrition rather than by any single decisive step.
- Filtration removes yeast physically, and only a sufficiently tight filtration removes enough of it to matter; a coarse polish reduces the population without preventing a restart.
- Sulphite in molecular form inhibits yeast metabolism, but its effectiveness depends on the pH of the cider and it acts on a population already reduced by other means — it is not a way of stopping a vigorous ferment.
- Keeving exploits the same principle by a different route: pectin gelation strips nitrogen and yeast into the chapeau brun, so the ferment beneath is starved from the start and arrests of its own accord with sugar remaining.
What it changes
The direction this step pushes the finished drink in, dimension by dimension. A direction, not a measurement: how far it moves depends on the juice, the temperature and how the step is carried out.
| Dimension | Direction | Why |
|---|---|---|
| Sweetness | Raises | Fructose, which the yeast has not consumed, remains in solution — and because fructose is the sweeter of the two principal apple sugars and is fermented later, an arrested cider is proportionally sweeter than its total sugar suggests. |
| Alcohol | Lowers | Sugar that is never fermented is sugar never converted to ethanol, so the drink finishes below the strength the starting gravity would have delivered. |
| Fruit character | Raises | A shorter fermentation evolves less carbon dioxide through the liquid and therefore strips fewer volatile esters and aldehydes before the yeast is removed. |
| Body | Raises | Residual sugar contributes directly to viscosity and to the perception of weight in the mouth, independently of any effect on sweetness. |
The chemistry and the organisms
What is actually being changed, and by what. Each entry says what that compound or organism does in cider generally; this page is one place it does it.
Compounds involved
Glucose
The sugar yeast takes first and the smallest of the three in apple juice, which is why the last sugar left in a slow ferment is almost never glucose.
Fructose
The dominant sugar of apple juice and the sweetest of the common sugars, which is why apple juice tastes sweeter than its total sugar figure implies and why a stuck ferment leaves sweetness behind.
Sulphur dioxide
The antimicrobial and antioxidant on which most modern cidermaking depends, and whose effectiveness collapses as pH rises — which makes every sulphiting decision a pH decision first.
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.
Carbon dioxide
The other product of fermentation, which protects a cider from air while it is being made and, dissolved in the finished drink, changes both its texture and its perceived acidity.
Organisms involved
Saccharomyces cerevisiae
The yeast that finishes essentially every cider, whether it arrives in a sachet or from the fruit, the press and the vessel.
Zygosaccharomyces bailii
A preservative-resistant spoilage yeast that refements sweetened cider and juice, and one of very few organisms able to grow through sorbate and benzoate at cider strength.
Saccharomycodes ludwigii
A large, sulphite-resistant yeast that refements sweet cider in bottle and is one of the classic causes of unwanted secondary fermentation.
Brettanomyces anomalus
The second Brettanomyces species regularly recovered from cider and beer, less studied than B. bruxellensis but capable of the same phenolic chemistry.
Where it is traditional
The places this step belongs to as a matter of practice. It is not a claim of exclusivity — a method can be traditional in one region and perfectly ordinary in another.
What can go wrong
Faults that begin at this step, or that this step makes more likely. Each one is set out with its causes and whether it can be put right.
Unwanted refermentation
Fermentation restarting in a sealed container, generating carbon dioxide that was not planned for and pressure that a bottle may not withstand.
Bottle over-carbonation
More dissolved carbon dioxide in the bottle than intended or than the glass is rated for — a presentation problem at the mild end and a physical hazard at the severe one.
Gushing
Cider that erupts from the bottle on opening, either because it is over-pressurised or because something in it is nucleating the dissolved gas violently.
Stuck fermentation
A fermentation that has stopped before the sugar is gone and will not restart, leaving a sweet, low-alcohol cider that is vulnerable to everything.
Excessive sediment
More deposit in the bottle or vessel than the presentation intends, ranging from a normal conditioning yeast layer to a loose sludge that clouds every pour.
Styles it produces
Categories in which this step is characteristic or required. Some name it in their definition; for others it is simply how they have always been made.
Cidre doux
The sweet tier of the French cider scale, defined since 2025 by a density at or above 1.024 together with an acquired strength no greater than 3% vol, so that the sweetness is demonstrably unfermented juice sugar.
Cidre demi-sec
The middle tier of the French cider scale, sitting between doux and brut on density and forming the commercial centre of ground for much French cider.
Keeved cider
Cider clarified before fermentation by a pectin gel that strips nutrients from the juice, producing a slow ferment that stops naturally with sugar still in solution.
Sweet cider
Cider in which sugar is the leading sensation, whether retained from an arrested fermentation, added after it, or produced by keeving.
Medium cider
Cider carrying enough residual or added sugar to be perceptible without dominating, the commonest sweetness level in British retail.
Poiré Domfront
The controlled appellation perry of the Domfrontais in southern Normandy, made predominantly from the Plant de Blanc pear on high-standard trees and finished sweet, low in alcohol and bottle-conditioned.
Ice cider
Cider made from apple juice concentrated by freezing, fermented slowly and stopped while a large residual sugar remains, giving a dessert-strength drink of high acid and high sweetness.
Quebec ice cider
Ice cider made under Quebec’s reserved designation, which sets out how the juice may be concentrated, what may be added and what the finished product must contain.
Ice perry
Perry made from pear juice concentrated by freezing, in which the fruit’s unfermentable sorbitol adds to the residual sweetness the arrested ferment leaves behind.
Low-alcohol cider
Cider at a reduced strength, reached either by removing alcohol from a finished cider or by arranging for less to be produced, with different consequences for flavour.
More on arrested fermentation
Sweetness in cider can be arrived at from either direction. A maker can ferment to dryness and add sugar, concentrate or fresh juice back — the route covered by `back-sweetening` — or can stop the ferment before the fruit’s own sugar is used up. The second route is more difficult and produces a different drink. The residual sugar is what the apples supplied, so its composition reflects the fruit: fructose predominates, because Saccharomyces consumes glucose preferentially and leaves fructose behind, and fructose is perceived as sweeter than glucose at the same concentration. The alcohol is correspondingly lower, and the aromatics are those of a short ferment rather than a full one. This is why cidre doux in Normandy tastes unlike a dry English cider sweetened to the same nominal sugar level.
The traditional method is attrition by racking, and it is slow. The cider is racked off its lees as soon as a compact deposit has formed, into a clean vessel, and racked again when a further deposit appears, each transfer removing yeast cells and the last of the available nitrogen until the surviving population cannot sustain a ferment. Cold assists at every stage, both by slowing the yeast and by making it settle. In Normandy the chapeau brun of keeving does the same job at the outset by stripping nitrogen into a floating gel, and the ferment beneath is arrested by starvation from the beginning rather than by intervention part-way. Modern production reaches the same endpoint faster, by chilling, centrifuging or filtering and then stabilising.
The risk has to be stated plainly because it is the defining property of the technique. An arrested cider is metastable. It contains sugar the yeast would consume if it could, and unless every viable cell has been removed or inhibited, it will eventually resume — sooner if it warms, sooner still if it is disturbed or if it picks up a sulphite-tolerant organism such as Zygosaccharomyces bailii or Saccharomycodes ludwigii, both of which are notably resistant to the doses that hold Saccharomyces down. That restart is welcome nowhere and dangerous in a sealed bottle. A maker producing sweet cider by arrest therefore has three honest options: keep it cold from cellar to glass, stabilise it properly by sterile filtration or pasteurisation, or accept the sweetness will not survive.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
Fermentation
Keeving
Forming a floating pectin gel that lifts nutrients and solids out of the juice, so that the ferment starves before it finishes and leaves natural sweetness behind.
Maturation
Racking
Moving cider off the sediment it has thrown, which both cleans the liquid and — by taking yeast and nitrogen away with the deposit — slows what is left of the ferment.
Maturation
Cold maturation
Holding cider at low temperature so that it settles bright, sheds colloidal material and stops changing microbially, without any additive or treatment being applied.
Stabilisation
Filtration
Passing cider through a porous medium to reach a stated visual brightness, at a real cost in colloidal material, body and aroma.
Stabilisation
Sulphite stabilisation
Managing free sulphur dioxide through maturation and at packaging so that a useful antimicrobial and antioxidant fraction survives into the bottle.
Blending
Back-sweetening
Adding sugar, juice or concentrate to a cider that has fermented dry — a straightforward adjustment that leaves the drink microbiologically unstable until something is done about it.
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 do i make my cider sweeter
- What is keeving — Keeving is a technique for starving a ferment of nitrogen so that it stops before all the sugar is gone, leaving a naturally sweet cider. Pectin is made to gel and float as a brown cap, carrying nutrients and yeast out of the juice with it.
- What is racking in cider making — Racking is siphoning cider off the sediment it has thrown into a clean vessel, leaving the lees behind. It clarifies the cider and, in traditional practice, is also used to slow a ferment by removing yeast with the lees.
- Does cider contain sulphites — Most does. Sulphur dioxide is added to protect juice and finished cider, and fermentation itself produces a small amount even when none is added. European labels must declare it above 10 mg per litre.
- 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.
- 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.
Where to go next
- How cider is made — The whole sequence, stage by stage, with the choices open at each one.
- Cider science — The chemistry and microbiology the methods on this page rest on.
- Troubleshooting — What goes wrong, how to recognise it, and whether it can be reversed.
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.
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.
The New Cider Maker’s Handbook: A Comprehensive Guide for Craft Producers
Claude Jolicoeur, Chelsea Green Publishing, 2013. ISBN 9781603584739 · reference work · bibliographic record verified, not opened 2026-08-25
Bibliographic record verified on 2026-08-25 against the Open Library union catalogue: Chelsea Green Publishing, 2013, ISBN 9781603584739, one edition recorded. That establishes the citation points at a real book in a stated edition, which is what a citation needs and is all it establishes. No copy was opened and nothing is quoted from it. The book itself is in print and not digitised in any open collection; where CiderHQ needs a figure from this territory it uses an accessible research source instead and says so.