Juice treatment
Juice clarification
The deliberate use of enzyme, fining agents or mechanical separation to produce a bright juice before fermentation, and what that costs the ferment.
Also called Pre-fermentation clarification, Juice fining, Bright juice preparation.
- Stage
- Juice treatment
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Body down, fermentation character down
- Safety
- None recorded
What it is
Where settling waits for gravity and accepts a partial result, clarification intervenes to get a juice that is actually bright. The usual routes are enzymic depectinisation followed by settling, addition of fining agents that flocculate the suspended load, centrifugation, or a combination. The end point is a juice with a low solids content and little colloidal material, of the kind a large juice plant would recognise. It is a deliberate manufacturing choice, and its consequences run all the way through the ferment to the finished cider, because what has been removed is not only turbidity.
Why it is used
- A bright juice ferments with far less risk of the coarse, sulphidic and vegetal characters that come from a heavy lees bed, which matters most where a clean, fruit-led cider is the target.
- Solids removal before fermentation gives a smaller, tighter lees deposit afterwards, so racking losses fall and the finished cider needs less downstream treatment to reach stability.
- Some products require it structurally: a filtered, sterile-filtered or pasteurised commercial cider is far easier to make from juice that was clean at the start than from one being chased clear at the end.
- Removing mould-affected and oxidised particulate reduces the load of taint precursors carried into fermentation.
How it works
- Enzymic depectinisation removes the colloidal protection around suspended particles, allowing them to aggregate and fall; this is usually the enabling step, because most fining and filtration performs poorly while pectin remains.
- Fining agents work by charge and by binding: gelatin and other proteinaceous agents complex with phenolics and settle, bentonite carries a negative surface charge that adsorbs positively charged protein, and silica sol is used to make protein flocs compact rather than fluffy.
- Centrifugation replaces gravity with an applied field, so particles that would take days to fall are separated in seconds, and the machine does it continuously rather than in batch.
- Every one of these removes more than turbidity. Suspended solids carry amino nitrogen, sterols and unsaturated fatty acids that yeast uses for membrane synthesis and stress tolerance, so a bright juice is a nutritionally poorer juice.
- Solids also act as nucleation sites for carbon dioxide release and as physical support for yeast in suspension; without them a ferment behaves differently even at identical temperature and pitching rate.
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 |
|---|---|---|
| Body | Lowers | Colloidal polysaccharide and suspended particulate contribute measurable weight and texture; a juice stripped of both ferments to a cider with less to hold on the mid-palate. |
| Fermentation character | Lowers | Fewer solids mean fewer reduced micro-environments and a lower load of yeast-derived coarse volatiles, so the ferment reads cleaner and more neutral. |
| Fruit character | Raises | With less suspended material to bind and mask volatiles, and less competing yeast-derived character, the fruit-derived esters sit more clearly in the aroma. |
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
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.
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.
Yeast-assimilable nitrogen
The nitrogen a yeast can actually use, which apple juice is chronically short of — the shortage behind both stuck fermentations and rotten-egg aromas, and the shortage keeving deliberately makes worse.
Amino acids
The largest usable nitrogen fraction in apple juice, and the raw material from which yeast builds both its own protein and most of the aroma compounds a cider carries.
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
Juice reception and settling tanks
A reception tank takes juice as fast as the press makes it so the rest of the plant can work at its own pace, and a settling tank then holds it still and cold while the gross solids fall — the cheapest clarification available to anyone.
Filters: plate, sheet, cartridge and crossflow
Filtration ranges from coarse polishing that only brightens a cider to sterile membrane filtration that removes yeast and bacteria entirely; the equipment differs in whether it traps particles in a depth of material or on a surface, and in what it takes out of the cider along with the haze.
The centrifuge
A centrifuge separates solids from liquid by spinning them at high speed, clarifying juice or cider in a single continuous pass without filter aid — fast, effective, expensive, and capable of doing real damage if it draws air.
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.
Nitrogen deficiency character
The set of characters a nitrogen-starved fermentation produces together — sulphide, a stalled or dragging ferment, harsh higher alcohols and a thin, hard cider.
Hydrogen sulphide
A rotten-egg or drain smell from hydrogen sulphide produced by stressed yeast, usually the first visible consequence of a nitrogen-short juice.
Sluggish fermentation
A fermentation that is still moving but far more slowly than it should, extending the period during which the cider is weak, sweet and exposed.
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.
Patulin contamination
Contamination of juice or cider with patulin, a mycotoxin produced by Penicillium expansum in rotting apples — a genuine food-safety question rather than a flavour one.
Pectin haze
A persistent, slightly viscous haze that will not settle, caused by pectin from the fruit remaining in solution as a colloid.
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.
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.
Apfelwein
The dry, sharp, still apple wine of Hesse, fermented out from culinary and local fruit and served in ridged glasses from a stoneware jug.
Modern American cider
The dominant contemporary American category: cider from culinary and dessert apples, fermented clean, often carbonated and frequently flavoured, defined against the heritage sector rather than by any tradition.
Australian cider
Cider from Australia, dominated by a large mainstream sector using dessert fruit and concentrate, with a smaller full-juice movement working from cool-climate orchards.
Eastern counties cider
Cider from eastern and south-eastern England made largely from dessert and culinary apples, giving a lighter, sharper and less tannic drink than the West Country tradition.
Irish cider
Cider from Ireland, dominated commercially by large-scale production from Armagh and imported fruit, with a smaller full-juice sector working from orchard-grown apples.
New Zealand cider
Cider from New Zealand, made in a country with a substantial export apple industry and a small but technically confident craft cider sector.
Sidra de nueva expresión
A modern Asturian category of filtered, clean, dry cider made with controlled fermentation and presented in a wine format rather than in the poured tradition.
Polish cider
Cider from Poland, a recent sector built on Europe’s largest apple crop and on dessert and culinary fruit rather than on an inherited cider tradition.
South African cider
Cider from South Africa, where a very large mainstream category built on Western Cape dessert fruit dominates and a small craft sector works alongside it.
More on juice clarification
It is worth stating the honest version of this rather than the marketing version. Heavily clarified juice does ferment faster, cleaner and more predictably, and it does produce a cider that is easier to filter, easier to stabilise and less likely to develop a haze in the bottle. It also ferments thinner. Those are the same fact seen from two sides. The suspended solids that make juice cloudy are also a reservoir of alpha-amino nitrogen, of sterols and unsaturated lipids that yeast incorporates into its membranes, and of the physical surfaces that keep yeast in suspension and give carbon dioxide somewhere to nucleate. Take them out and the yeast is working in a leaner, more demanding medium.
Where that leads depends on the fruit. Cider juice starts nitrogen-poor by comparison with grape must, so clarification pushes an already marginal nitrogen budget lower, and the classic result is a ferment that starts briskly, throws hydrogen sulphide part way down, and then slows to a crawl or stops. Producers who clarify hard therefore almost always feed, which is why juice clarification and nutrient addition tend to travel together as a pair of decisions rather than separately. The alternative — accept a cloudy juice and let it feed its own ferment — is not primitive; it is a different arrangement of the same nutritional accounting.
Traditions divide roughly along the line of what the finished cider is meant to be. German juice technology and Apfelwein production, and large-scale cider production anywhere, clarify as a matter of course because the product is defined by brightness and consistency. Normandy keeving works towards a clear juice too, but by a completely different route that removes nitrogen deliberately in order to arrest the ferment, so the low-nutrient outcome is the objective rather than a side effect. Asturian sidra natural and English farmhouse practice largely do not clarify at all, fermenting on solids and accepting the coarser, more fermentative character that follows. None of these is a defective version of another.
What a practitioner actually decides is how far to go and whether to compensate. Partial clarification — enzyme plus a cold settle, racked once — keeps a workable share of the nutrient while removing the grossest material, and for many small producers that is the sensible middle. Going all the way to a centrifuged bright juice is a commitment: it implies nutrient management, probably temperature control, and usually a stabilisation regime at the end. The failure mode to avoid is clarifying hard and then treating the ferment as if nothing had changed.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
Juice treatment
Pectinase treatment
Adding pectin-degrading enzyme preparations to juice so that haze-forming and viscosity-forming pectin is broken down before fermentation.
Juice treatment
Juice settling
Letting freshly pressed juice stand cold and undisturbed so that gross solids fall, then racking the cleaner juice off the deposit before pitching.
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.
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.
Juice treatment
Nutrient addition
Supplementing a characteristically nitrogen-poor juice so that yeast can complete fermentation without producing sulphide or stalling.
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.
- Is cider vegan — Cider itself is a plant product, but some producers clarify it with animal-derived finings such as gelatine, isinglass or chitosan. Vegan status therefore depends on the fining regime, which is why some ciders are certified and others are not.
- 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.
- How do i get rid of the sulphur smell in my cider — Racking with a little splashing usually blows off free hydrogen sulphide while it is still fresh. Once it has reacted into mercaptans the smell becomes rubbery and no longer responds to aeration.
- What does a nitrogen-starved cider taste like
- 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 yan and why does cider juice run short of it — Yeast assimilable nitrogen is the nitrogen yeast can actually use. Apple juice is usually short of it — in one Virginia survey of 108 samples, 94 per cent fell below the level wine practice treats as a minimum — which is why cider ferments stall more readily than wine ferments.
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.
Hochschule Geisenheim University — beverage technology
Hochschule Geisenheim · university · retrieved 2026-08-24
German beverage-technology research covering apple wine and fruit juice processing, including the enzymology of clarification.
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 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.