Pressing
Belt pressing
Continuous pressing in which enzyme-treated pomace is carried between two converging porous belts and progressively dewatered around a series of rollers.
Also called Belt press, Continuous belt press.
- Stage
- Pressing
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Phenolic character up, oxidative character up
- Safety
- None recorded
What it is
A belt press is a dewatering machine rather than a batch press. Pomace is fed as a continuous stream onto a moving porous belt, drains freely for a first stretch under gravity alone, and is then met by a second belt travelling at the same speed. The two belts converge and pass together around a sequence of rollers of decreasing diameter, so the pomace sandwiched between them is subjected to rising compression and, on each roller, to a shearing displacement between the belt faces. Juice passes through the belt fabric to collection trays below, and the spent cake is scraped off at the discharge end. Nothing is loaded, built or stripped: the machine runs for as long as fruit is fed to it.
Described in full
- Shape
- A two-axis plot. The horizontal axis runs from little air contact on the left to a great deal on the right; the vertical axis runs from slow at the bottom to fast at the top. Five presses are plotted as marks: circles for batch presses, a circle in a different fill for the closed bladder press, and a diamond for the continuous belt press.
- Rack and cloth
- Low on both axes. The pomace is built into cloth-wrapped layers by hand and pressed slowly; the cheese is a largely sealed stack, so the juice inside meets little air. It gives clean juice and it is the slowest thing in the building.
- Basket and hydraulic
- Both batch methods, both slow, both with the pomace surface exposed while pressure is applied. The hydraulic press is the faster of the two because the pressure is applied mechanically rather than by a screw.
- Bladder
- The lowest air contact of all, because the press is a closed vessel and can be flushed or filled without the juice seeing much oxygen at all. Faster than the batch presses and slower than a belt.
- Belt
- The fastest and the most exposed. Pomace runs continuously between two moving belts through a series of rollers, in the open, in a thin layer with a large surface area. That is the trade: the juice is out quickly and it has met a great deal of air on the way.
- Why there are no numbers
- Throughput and yield figures for presses circulate widely and come almost entirely from manufacturers. CiderHQ has verified none of them and does not reproduce them. What can be defended without a number is the ordering, and the ordering is the useful part: the trade between speed and oxidation is the decision a maker is actually taking.
Why it is used
- Throughput is continuous rather than cyclic, which is what large-volume production needs when a whole day’s milling has to move through pressing without a queue.
- Labour per tonne is very low, because the whole build-and-strip cycle that a batch press demands simply does not exist.
- The combination of pressure and inter-belt shear extracts efficiently from pomace that has been enzymatically loosened, giving high recovery in a single pass.
- The machine cleans down in place and holds a consistent output over a long run, which suits juice going to a blended, specified product.
How it works
- The gravity drainage zone removes the free juice first, so the material entering the pressing zone is already a handleable cake rather than a slurry that would extrude sideways out of the belts.
- Each roller reduces the gap between belts, raising the compressive stress step by step rather than all at once; the wedge geometry between rollers does the same continuously.
- As the belts wrap a roller, the outer belt travels slightly further than the inner one, and the resulting differential motion shears the cake, breaking the compacted layer and opening new drainage paths.
- Pectin in untreated pomace binds water into a gel that will not release under a rolling nip, so pectolytic enzyme is used ahead of the press to degrade the pectic network and free that water; without it the cake blinds the belt and dewatering stalls.
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 |
|---|---|---|
| Phenolic character | Raises | Roller compression combined with inter-belt shear extracts from ruptured skin and cortical tissue as well as from free juice, carrying additional flavanols and hydroxycinnamic acids into the run. |
| Body | Either way | The press itself drives a heavy fine-solids and colloid load into the juice, but the enzymatic depectinisation that precedes it and the clarification that usually follows strip much of that back out again. |
| Oxidative character | Raises | Pomace and juice are spread in thin films across open belts and trays with a large surface area exposed to air, which is close to ideal conditions for polyphenol oxidase activity. |
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.
Pectin lyase
The chain-cutting activity in a commercial pectinase preparation, which raises press yield and clears a juice by destroying the colloid pectin creates — and destroys the possibility of keeving in the same stroke.
Pectin methylesterase
The enzyme that strips methyl groups from pectin, exposing the charged sites that calcium bridges — which is the reaction the whole of keeving is built on.
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.
Galacturonic acid
The sugar acid that pectin chains are built from, released as they break down, and a significant part of why juice from rotten fruit binds so much of the sulphite added to it.
What it is done with
The belt press
A continuous press in which mash travels between two porous belts through a series of rollers of decreasing gap, squeezing juice out sideways; very high throughput and very high oxygen exposure.
The pomace belt, and what becomes of pomace
Pressed cake leaves a modern press on a belt or an auger and goes to stock feed, to land, to anaerobic digestion or to pectin extraction; on a farm it usually goes to cattle or back on the orchard, and neither is as simple as it is usually described.
Press types compared
A side-by-side account of how the common press types differ in yield, in oxygen exposure, in the phenolic load they put into the juice, in labour and in what they demand of the mill.
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.
Oxidation
The cumulative effect of oxygen on finished cider: fruit aroma flattens, colour deepens towards amber, and a bruised-apple or sherry-like character replaces the fresh one.
Enzymatic browning
The rapid darkening of milled fruit and fresh juice as polyphenol oxidase converts phenolics to quinones, taking colour and some tannin structure with it.
Pectin haze
A persistent, slightly viscous haze that will not settle, caused by pectin from the fruit remaining in solution as a colloid.
Excessive astringency
A drying, roughening, mouth-puckering sensation that outstays its welcome, produced by larger phenolic polymers precipitating salivary proteins.
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.
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.
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.
More on belt pressing
Belt pressing is the industrial answer to the problem that batch pressing does not scale gracefully. A rack-and-frame or pack press has a fixed cycle time no matter how large the frame is, and every cycle has dead time in loading and stripping. A belt press has no cycle: fruit goes in one end at a steady rate and cake comes off the other, and the constraint moves from the press to the mill and the pump. That is why almost all high-volume juice and cider production, and effectively all apple concentrate production, is belt-pressed, while almost no traditional or small-parcel cider is.
The enzyme requirement is not incidental — it is what makes the geometry work, and it is what places belt-pressed juice at the opposite end of the spectrum from keeving. Keeving depends on native pectin methylesterase acting slowly on intact pectin to build a calcium pectate gel that floats as a chapeau brun, and it fails outright in the presence of added pectolytic enzyme. Pomace prepared for a belt press has had exactly that pectin deliberately dismantled. A producer therefore chooses at the mill, not at the tank: pomace conditioned for continuous pressing cannot afterwards be keeved, and juice intended for keeving cannot be belt-pressed well.
The juice itself reflects the machine. High recovery means a large proportion of what the fruit held is extracted, including material from tissue that a gentler press would leave behind, and the shearing action carries a heavy load of fine solids into the tray. Belt-pressed juice therefore normally goes straight to settling, enzymatic clarification, centrifugation or filtration rather than to a vessel as it stands. Where a maker wants a juice that is stable, consistent, cheap to produce and destined for a filtered, blended product, that is a coherent set of choices; where the aim is a naturally clarifying farmhouse or cidre bouché ferment, the same choices remove the mechanism the tradition depends on.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
Fruit preparation
Enzyme addition to pomace
Dosing pectin-degrading enzyme into milled pomace rather than into juice, to raise press yield and change how the cake drains.
Fruit preparation
Pomace conditioning
Letting milled pomace stand before it goes to the press so that it drains better, presses faster and gives more juice.
Juice treatment
Pectinase treatment
Adding pectin-degrading enzyme preparations to juice so that haze-forming and viscosity-forming pectin is broken down before fermentation.
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.
Pressing
Pressing yield
The proportion of a fruit charge recovered as juice, and why a single headline figure for it is not a meaningful number.
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.
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 pressing yield — Pressing yield is the proportion of fruit weight recovered as juice. It varies from under half on a poorly loaded basket press to around seventy per cent on a well-run rack-and-cloth or belt press.
- Which type of cider press should i use — No press is best. Each one sits at a different point on four trade-offs: how much juice it recovers, how much air the juice meets, how hard it works the solids, and how much labour and capital it needs.
- How do i clear a cloudy cider
- 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 oxidation in 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.
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.