Pressing
Hydraulic pressing
Pressing in which a pump drives fluid against a ram, so that a small pumped pressure becomes a large, controllable and repeatable load on the pomace.
Also called Pack press, Ram press, Hydraulic rack press.
- Stage
- Pressing
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Phenolic character up, astringency up
- Safety
- Carries a safety consideration — see below
A hydraulic press is a crush hazard and a stored-energy hazard at the same time. The platen closes with force that no part of a body can resist and no reflex can escape, so nothing should ever be reached in to adjust while the ram can move, and interlocks and guards must not be defeated to save a pressing cycle. The circuit itself stays loaded after the pump stops: hoses, seals and fittings hold pressure, a pinhole leak can inject fluid through skin, and any maintenance requires the system depressurised and the ram mechanically supported rather than merely lowered. Treat hose failure and platen movement as the two things to stand clear of.
What it is
A hydraulic press substitutes a pump, a fluid circuit and a ram for the screw and the bar. Oil or water delivered under pressure to a cylinder pushes a piston whose face area is far greater than that of the pump element, and the ram carries the platen up or down against the pomace stack. In the pack or rack-and-frame configuration the stack itself is unchanged from the older method — cloth-wrapped beds separated by wooden or plastic racks — but the operator now sets a pressure on a gauge and holds it, rather than judging load by how hard the bar has become to move.
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
- It supplies far higher and far steadier loads than a person on a bar can, which makes a fuller extraction from the same fruit practical.
- Pressure is a number on a gauge rather than a feel in the hands, so a pressing programme can be recorded, repeated across a season and handed to another operator.
- Holding a set pressure while the bed consolidates does the waiting that a screw press requires the operator to do by hand.
- The same frame handles fruit of very different pomace texture, from soft dessert apples to fibrous perry pears, by changing the pressure ramp rather than the equipment.
How it works
- A confined fluid transmits pressure equally in all directions, so the force at the ram is the circuit pressure multiplied by the piston area — the geometry of the cylinder, not the strength of the operator, sets the load.
- Because the fluid is effectively incompressible, ram travel tracks the volume pumped, and the press can hold a constant pressure while the pomace bed continues to consolidate and drain beneath it.
- Compression collapses the pore network in the pomace; juice flows out along the cloth faces under the pressure gradient until the remaining liquid is held by capillary and cell-wall forces that the press cannot overcome.
- Late in the cycle the bed is dense and permeability has fallen sharply, so additional pressure buys progressively less juice and increasingly extracts material from ruptured tissue rather than free liquid.
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 | High terminal pressures rupture skin and parenchyma tissue that a gentler press leaves intact, releasing flavanols and hydroxycinnamic acids that would otherwise stay bound in the pomace. |
| Astringency | Raises | The hard-pressed late fraction carries a higher proportion of polymerised procyanidins, which are the phenolics that cross-link salivary proteins and produce a drying tactile response. |
| Body | Raises | Severe compression drives soluble pectin and fine cell-wall fragments into the juice, raising colloidal load and giving a fuller mouthfeel before any clarification is done. |
| Oxidative character | Raises | Juice from an open rack-and-frame stack runs across trays in contact with air throughout a long cycle, giving polyphenol oxidase ample opportunity to act before the juice is collected. |
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
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.
Procyanidins
The condensed tannins of cider fruit, whose chain length — not their quantity — decides whether the mouth registers bitterness or astringency.
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.
Polyphenol oxidase
The copper enzyme that turns cut apple brown within seconds, and the reason a cidermaker has to decide, at the press, whether to let the juice oxidise or to stop it.
Dissolved oxygen
Essential to a healthy yeast population at the start of fermentation and the principal enemy of a cider from the moment fermentation ends.
What it is done with
Hydraulic packs and rams
The pump, reservoir, valves, hoses and ram that turn a small electric or hand effort into tonnes of force at a press platen — the component that made high-yield batch pressing practical, and the one that stores the most energy.
The rack and cloth press
A press in which pomace is built into a stack of thin cloth-wrapped layers separated by rigid racks, so that juice has a short path to a free edge at every level — the highest-yielding batch press for traditional coarse pomace.
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.
Excessive astringency
A drying, roughening, mouth-puckering sensation that outstays its welcome, produced by larger phenolic polymers precipitating salivary proteins.
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.
Euskal Sagardoa
Basque cider under its own protected designation, made from Basque-grown apples in the sagardotegi tradition of barrel service and dry, high-acid, still cider.
Herefordshire cider
Cider from the county with England’s largest cider orchard area, protected as a geographical indication and spanning farmhouse practice, bottle-fermented cider and industrial-scale production.
More on hydraulic pressing
The hydraulic pack press is the machine that carried twentieth-century cider. It arrived as farm and factory pressing scaled past what timber and screw threads could bear, and for most of that century it was simply what a cider works had: a frame, a ram, a stack of cloths, and a pressing cycle written down and followed. It displaced the screw not because the extraction principle changed — it is still a bed of pomace being squeezed — but because the fluid circuit decoupled the load from the operator. A screw press is limited by what a person can turn and a frame can take; a hydraulic circuit is limited by the pump, and adding pressure costs nothing in labour.
What the operator actually decides is the shape of the ramp. A rapid rise to full pressure seals the outer faces of each bed, traps juice behind a compacted skin, and pushes fines through the cloth into the tray; the pressing then runs long and the juice arrives turbid. A staged ramp, with holds long enough for each pressure step to drain out, gives both a better run and a cleaner one. The other decision is where to stop. Extending the cycle at high pressure raises yield, but the juice coming off at the end is not the same liquid as the free run: it is proportionally richer in phenolics and cell-wall material pressed out of macerated tissue, and in some houses that final fraction is kept separate and blended back deliberately, or not at all.
Compared with a pneumatic or membrane press, a pack press works the pomace harder and exposes the running juice to air across open trays, so hydraulic-pressed juice tends to sit further towards oxidative colour and phenolic extraction. That suits a tannic West Country or Normandy blend, where those compounds are the point, considerably better than it suits a pale aromatic single varietal. It is also, at any scale, the least forgiving press to be careless around, because the energy that makes it useful is stored in a circuit that gives no warning before it releases.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
Pressing
Rack-and-cloth pressing
Building pomace into thin cloth-wrapped layers separated by racks, so that juice has a short path out and the stack can carry the pressure needed to force it.
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.
Fruit preparation
Milling
Reducing whole fruit to a pulp so that the press has cell walls it can drain, rather than intact apples it can only bruise.
Pressing
Pomace handling
What is done with the pressed cake once the juice is off it — feed, pectin extraction, composting, digestion or orchard spreading — and why a wet acidic heap beside the press is a problem.
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.
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 are apples pressed for cider — The fruit is first milled to a pulp, then that pulp is squeezed — traditionally in cloth-wrapped layers under a screw or hydraulic ram, and industrially in a belt or bladder press. Whole apples cannot be pressed usefully; they must be broken first.
- How are apples milled for cider
- 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.
- What is a rack and cloth press and why is the pomace built in layers — The pomace is spread on a square cloth laid in a shallow forming frame, the cloth corners are folded over to make a flat parcel, a slatted rack is laid on top, and the process repeats until a stack — the *cheese* — is built. The whole stack is then compressed, usually by a hydraulic ram.
- 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
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.
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.
Hereford Museum of Cider collections and interpretation
Hereford Cider Museum Trust · museum · retrieved 2026-08-24