Carbonation
Priming
Adding a measured, calculable quantity of fermentable sugar at bottling so that the fermentation which follows generates a predictable volume of carbon dioxide.
Also called Priming sugar, Tirage addition, Dosage de tirage.
- Stage
- Carbonation
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Carbonation up, alcohol up
- Safety
- Carries a safety consideration — see below
Priming generates pressure inside a sealed container and an over-dose will burst it. Use bottles specified for sparkling products and closures rated to match, never still-wine bottles or screw-capped containers. The danger is compounded when a cider that has not actually finished fermenting is primed, because the residual sugar adds to the calculated dose and the total can be several times what was intended: confirm with repeated stable gravity readings, taken over days rather than hours and at cellar temperature, that fermentation has genuinely stopped before adding anything. Blend the addition thoroughly so no bottle receives a concentrated dose, store the filled bottles cool, keep them out of living and working spaces while they condition, and wear eye protection when handling them.
What it is
Priming is the addition of a known amount of fermentable sugar — as sucrose, as dextrose, as fresh juice or as apple juice concentrate — to a finished cider immediately before it is sealed into its container, so that the yeast present ferments that sugar and produces a calculated quantity of carbon dioxide. It differs from bottling on residual sugar in one decisive respect: the quantity is added deliberately and is therefore known, rather than estimated from what happens to be left in the cider. It is the arithmetic step underlying bottle conditioning, the traditional method and tank conditioning alike.
Why it is used
- It converts carbonation from a guess into a calculation, because the mass of sugar added determines the mass of gas produced.
- It allows a cider that has fermented completely dry and been racked clear to be carbonated by fermentation, which would otherwise be impossible with no sugar left.
- It gives a small producer a route to a sparkling cider with no pressure equipment beyond the bottles themselves.
- Using juice or concentrate rather than refined sugar returns a little apple character along with the fermentable material, which some makers prefer for a cider sold as unadulterated.
How it works
- Fermentation of sugar to ethanol and carbon dioxide proceeds in a fixed molar ratio, so a given mass of fermentable sugar yields a predictable mass of gas. That is the basis of every priming calculation.
- The gas produced distributes between the liquid and the headspace according to Henry’s law at the storage temperature. Mass of gas, liquid volume, headspace volume and temperature together determine the pressure the container reaches, which is why priming tables always specify a temperature.
- Because the sugar is added to a cider that has already fermented out, the yeast population is small and the fermentation is slow, which is what allows the gas to dissolve rather than to be produced faster than it can go into solution.
- The first failure mode is arithmetic: if the cider still holds fermentable sugar of its own, the total is the residual plus the addition, and a calculation based only on the addition understates the pressure — sometimes badly.
- The second is mixing. Sugar syrup is denser than cider and will sit at the bottom of a tank unless it is thoroughly and gently blended before filling, so the first bottles off the line receive less than intended and the last receive far more.
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 |
|---|---|---|
| Carbonation | Raises | The added sugar is fermented in a sealed container, so the gas it yields is retained in solution rather than escaping as it would in an open vessel. |
| Alcohol | Raises | Ethanol is produced alongside the carbon dioxide in fixed proportion, so the finished cider is slightly stronger than the base it was made from. |
| Fermentation character | Raises | A fresh, if small, fermentation in the package produces new esters and leaves a yeast deposit whose slow autolysis adds a bready note over time. |
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
Sucrose
The disaccharide of apple juice and the sugar most often added to it, split into glucose and fructose by the yeast’s own invertase before any of it is fermented.
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.
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.
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.
Organisms involved
What it is done with
The hydrometer and the trial jar
A weighted glass float that sinks to a depth set by the density of the liquid, read against a scale on its stem; with a starting and a finishing reading it gives the sugar consumed and an estimate of alcohol produced.
Crown caps, swing tops and the tools that fit them
The crown cap is a crimped steel cap with a compressible liner, the cheapest reliable pressure closure ever devised; the swing top is a reusable stopper held by a wire bail, convenient and dependent entirely on the condition of its gasket.
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.
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.
Under-carbonation
A cider intended to sparkle that has little or no dissolved gas, usually because the bottle conditioning never started or the closure did not hold.
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.
Unwanted refermentation
Fermentation restarting in a sealed container, generating carbon dioxide that was not planned for and pressure that a bottle may not withstand.
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.
Bottle-conditioned cider
Cider that completes a fermentation inside its sealed bottle, generating its own carbonation and, in most cases, leaving a yeast deposit behind.
Bottle-conditioned perry
Perry that completes its fermentation in the sealed bottle, generating carbonation and lees character while the fruit’s sorbitol keeps a sweetness the yeast cannot remove.
Sparkling cider
Cider carrying enough dissolved carbon dioxide to produce a persistent bubble, by bottle fermentation, tank fermentation or injection.
Pétillant cider
Lightly carbonated cider in which the gas is felt as a prickle rather than a stream of bubbles, the level most traditional bottle fermentation reaches on its own.
Graff
A hybrid of cider and beer, fermented from apple juice with malt and usually hops, originating in North American homebrewing rather than in any orchard tradition.
More on priming
Priming is the only carbonation method that is fundamentally an arithmetic exercise, and the arithmetic is genuinely simple. Yeast converts sugar to ethanol and carbon dioxide in a fixed proportion, so the mass of gas produced follows directly from the mass of fermentable sugar added. That gas then has to go somewhere: part dissolves into the cider, part occupies the headspace, and the split between them is set by temperature through the same solubility relationship that governs forced carbonation. Knowing the liquid volume, the headspace and the storage temperature, a maker can predict the pressure. Published conventions for the calculation — the form given in Jolicoeur’s handbook is the one most widely used by small producers — package that relationship into a usable table.
What the arithmetic cannot do is check its own inputs, and both of the ways priming goes wrong are input errors rather than errors of method. The first is the residual sugar problem. A calculation assumes the cider contains no fermentable sugar of its own, and if that assumption is false the true dose is the residual plus the addition. A cider that has merely gone quiet — cold, or short of nutrient, or with a yeast that has flocculated out — is not a finished cider, and it will resume in a warm bottle with the priming sugar on top of what it already held. Stable gravity readings taken over several days at cellar temperature are the only defence, and a single reading proves nothing.
The second is mixing, and it is the one that produces a batch where most bottles are correct and a handful are dangerous. Sugar syrup is denser than cider and will stratify in a bottling tank; unless it is blended through the whole volume gently enough not to knock the gas out and thoroughly enough to be uniform, the dose varies down the run. The traditional bulk-priming approach — dissolving the sugar, adding it to the receiving vessel and racking the cider onto it so the transfer itself does the mixing — exists precisely to address this. The alternative, dosing each bottle individually, is slow but removes the stratification problem entirely, and remains common among makers working at a scale where counting bottles is realistic.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
Carbonation
Bottle conditioning
Carbonating cider by letting a second fermentation finish inside the sealed bottle, so the gas is generated where it is going to stay.
Carbonation
Natural carbonation
Bottling before the primary fermentation has finished, so the sugar still in the cider produces the carbonation with nothing added and nothing restarted.
Carbonation
Traditional method
A second fermentation in the bottle the cider will be sold in, followed by riddling the deposit into the neck and expelling it, so the drink is both bottle-fermented and clear.
Carbonation
Tank conditioning
Running a second fermentation in a sealed pressure tank so the gas is generated by yeast but the sediment never reaches the bottle.
Packaging
Bottling
Transferring finished cider into glass, where the dominant variable is how much oxygen the liquid picks up in the few seconds it takes to fill and close each bottle.
Packaging
Bottle pressure management
Matching the pressure a carbonated cider will actually generate to glass that can contain it, taking account of temperature and of any fermentable sugar left in the bottle.
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 is sparkling cider made
- How much pressure builds up in a bottle of cider — Enough to matter. Every gram of sugar fermented in a sealed bottle produces gas, and a bottle not rated for it can fail. The French cider appellations require a minimum of 1.0 to 1.5 bar at 20 °C, and a bottle-conditioned cider can go well beyond that if it was filled with more sugar than intended.
- 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.
- Why did my cider bottles explode — Because fermentable sugar was still present, or too much priming sugar was used, and the pressure exceeded what the bottle could hold. Never bottle a cider whose gravity is still falling, and never use bottles not designed for pressure.
- How do i use a hydrometer to measure cider — A hydrometer floats at a depth determined by the density of the liquid it is in. Sugary juice is denser than water, so the hydrometer floats high; as fermentation converts sugar to alcohol the density falls and it sinks.
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 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.
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.