Stabilisation
Fining
Adding a reactive agent that binds a target colloid and carries it to the bottom, chosen according to whether the problem is tannin, protein or a phenolic taste fault.
Known as Collage where it originates. Also called Clarification with fining agents, Collage.
- Stage
- Stabilisation
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Astringency down, bitterness down
- Safety
- Carries a safety consideration — see below
Isinglass is derived from fish and gelatin from animal collagen. Where residues may persist in the finished drink, allergen declaration obligations apply and differ by jurisdiction; check the requirements in force in the market of sale before choosing an agent.
What it is
Fining introduces a substance chosen to react with something already dissolved or suspended in the cider, forming an aggregate heavy enough to settle. It is chemistry rather than mechanical separation: the agent is not a sieve but a partner, selected because it carries the opposite charge to the target or because it adsorbs a particular class of molecule. Some agents are proteins, some are clays, some are synthetic polymers, and some are used in pairs whose opposing charges do the work between them. What settles is drawn off by racking, so fining always costs a little volume as lees.
Why it is used
- It clears hazes that will not settle by gravity, because the particles causing them carry like charges and repel one another rather than aggregating.
- It allows a targeted reduction in bitterness or astringency in a cider whose phenolic load is out of balance, without the general stripping that a tight filtration would cause.
- It removes the specific precursors of a haze that would otherwise appear later in the package, which is a stabilisation aim rather than a cosmetic one.
- It can correct a colour fault — notably pinking in a light-coloured cider — where filtration would not touch the responsible compounds.
How it works
- Gelatin and isinglass are positively charged proteins at cider pH. They bind negatively charged tannin, and the resulting protein–tannin complex grows until it is dense enough to fall. This is the same reaction that produces astringency on the palate, run deliberately in the tank instead.
- Bentonite is a negatively charged swelling clay with an enormous sheet surface area. It binds positively charged protein, so it is the agent for a protein haze — and, being the mirror image of gelatin, it is also what removes gelatin that has been over-added.
- PVPP is a synthetic polymer that adsorbs phenolics selectively through hydrogen bonding, favouring the smaller catechins and their oxidation products. It is used to lower bitterness or to fix pinking without taking out the larger procyanidins that carry structure.
- Kieselsol, a negatively charged silica sol, is paired with chitosan or gelatin: the positive and negative species flocculate one another and sweep suspended matter down with them, which compacts the lees and clears the liquid faster than either alone.
- Overfining occurs when the agent is added beyond what the target can consume. The unreacted excess — most often protein — stays in solution and later comes out of it as a haze in the bottle, so the fining that was meant to stabilise the cider destabilises it.
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 |
|---|---|---|
| Astringency | Lowers | Protein fining agents bind the same tannins that would otherwise bind salivary proteins in the mouth, so the tannin is removed before it can produce the drying sensation. |
| Bitterness | Lowers | PVPP adsorbs the smaller phenolics most associated with bitter taste, so the reduction falls disproportionately on bitterness rather than on structure. |
| Body | Lowers | Every fining takes colloidal material out of solution with the target, and colloids are part of what gives cider palate weight. |
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
Tannin–protein complexes
What astringency physically is: long tannin chains cross-linking salivary proteins and precipitating them, which is also the mechanism behind fining, protein haze and the classic cider-and-cheese pairing.
Procyanidins
The condensed tannins of cider fruit, whose chain length — not their quantity — decides whether the mouth registers bitterness or astringency.
Total phenolics
The single number used to summarise everything phenolic in a juice, useful for comparing fruit and misleading whenever it is used to predict how a cider will taste.
Pectin
The structural polysaccharide of fruit cell walls, which decides how much juice a press releases, whether a cider ever clears, and whether keeving is possible at all.
Beta-glucan
The bacterial exopolysaccharide behind ropiness, which turns a cider oily and thread-like without changing how it smells or tastes.
What it is done with
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.
Protein haze
A fine haze that forms as protein and tannin combine into insoluble complexes, often appearing in a cider that had already been clear.
Pinking
An unexpected pink or salmon tint developing in a pale cider or perry, associated with oxidation of colourless phenolic precursors.
Colour loss
A cider left noticeably paler than it should be, usually because fining, filtration or sulphite has removed the phenolic material that gave it colour.
Thin body
A cider with no weight or texture in the mouth, most often from over-watered pomace, low-gravity juice or a blend with nothing to give it substance.
Excessive astringency
A drying, roughening, mouth-puckering sensation that outstays its welcome, produced by larger phenolic polymers precipitating salivary proteins.
Excessive bitterness
Bitterness that dominates the palate rather than supporting it, usually from a blend weighted too heavily towards high-tannin fruit or extracted too hard.
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.
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.
Yeast haze
Cloudiness from yeast cells that have not settled out, usually because the strain flocculates poorly or the cider has not been left alone long enough.
Metal haze
A haze or dark cast caused by dissolved iron or copper picked up from equipment, forming insoluble complexes with phosphate or with the cider’s phenolics.
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.
Still cider
Cider with no perceptible dissolved carbon dioxide, presented as a fermented fruit drink whose texture rests on body, acid and tannin alone.
Modern mainstream cider
The industrially produced, consistent, carbonated cider that accounts for most of what is sold worldwide, generally made partly from concentrate and finished to a fixed specification.
Sweet cider
Cider in which sugar is the leading sensation, whether retained from an arrested fermentation, added after it, or produced by keeving.
Unfiltered cider
Cider packaged without filtration, retaining suspended yeast and fine solids and the body and aroma that come with them.
More on fining
Colloidal haze persists because the particles causing it are electrically alike. Each carries the same sign of surface charge, so each repels its neighbours, and a suspension of mutually repelling particles will stay suspended almost indefinitely. Every fining agent is an answer to that: introduce something of the opposite charge, the repulsion collapses, aggregates form and gravity finally has something heavy enough to act on. Knowing the sign of the problem is therefore the whole of the skill. A protein haze treated with gelatin gets worse, because gelatin is itself protein. A tannin problem treated with bentonite is barely touched. The agent must be matched to the constituent, and the constituent identified before the agent is chosen.
The traditions differ over whether fining is a normal step at all. Norman and Breton practice largely sidesteps it: keeving strips nutrients and pectin from the must through the chapeau brun, and a cider fermented from that must tends to fall bright of its own accord, so the French cellar reaches clarity by fermentation management rather than by addition. Asturian and Basque sidra natural is not fined, and the cloud is part of the product. English and North American practice uses fining routinely, and the pairing of kieselsol with chitosan has spread widely among small producers partly because chitosan is of fungal or crustacean origin rather than animal, and partly because the pair compacts lees tightly enough to lose less cider to the racking.
A trial before a full addition is not a formality. The correct dose for a given cider cannot be read off a table, because it depends on how much of the target constituent is present, and adding more than that quantity is the classic way to create the very fault the fining was meant to prevent: unreacted gelatin left in solution comes out later as a protein haze in a bottle already in the trade. Bentonite will pull that excess back out, but the cider has then been fined twice and has lost body twice. The other cost is sensory and permanent. Fining removes phenolic material, and phenolic material is where much of a bittersweet cider’s structure lives, so a cider fined to brilliance can end up correct in appearance and hollow in the mouth.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
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
Cold stabilisation
Holding cider cold before packaging so that anything which would fall out of solution in a cold warehouse falls out in the tank instead.
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.
Blending
Tannin balancing
Setting the phenolic structure of a blend, which means handling bitterness and astringency separately because they are different perceptions produced by different sizes of the same molecules.
Stabilisation
Centrifugation
Separating solids from cider by density in a rapidly spinning bowl, continuously and without a filter medium, at the price of shear and oxygen pick-up.
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.
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.
- 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.
- What are procyanidins in cider — They are the condensed tannins of apples: chains of catechin-type units whose length decides how much of the phenolic load reads as bitterness and how much as astringency. Two ciders with identical total tannin can taste nothing alike.
- What does pectin do in cider — Pectin is the structural polysaccharide that holds fruit cells together. In juice it holds haze in suspension, and it is the molecule keeving depends on: strip its methyl groups and it will gel with calcium and float the nutrients out of the juice.
- What is sweet cider in america — In the United States and Canada, sweet cider means fresh, unfermented, usually unfiltered apple juice, with no alcohol in it. In Britain the same phrase means a fermented cider with residual sugar.
- Do i need a filter to make cider
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.
Regulation (EU) No 1169/2011 on the provision of food information to consumers
European Union · legislation · passage verified 2026-08-24
The instrument behind the "contains sulphites" declaration and the alcoholic-strength labelling rule. Read on 2026-08-24 in the assimilated text maintained on legislation.gov.uk, which is the version in force for Great Britain and keeps the EU numbering. Two provisions matter to cider and both are widely misquoted: the sulphite threshold is 10 mg/L rather than a percentage, and a labelled cider strength carries a tolerance of a full percentage point either way — twice what still grape wine is allowed.