Equipment

The bladder or pneumatic press

How does a pneumatic cider press work and what does it do to the juice?

In short

A pneumatic press is a horizontal cylinder containing a flexible membrane along one side or down the axis. Pomace is loaded into the space around it, and the membrane is inflated with compressed air so the mash is pressed outward through perforations in the drum wall, or into internal drainage channels covered with a screen.

The distinctive property is gentleness. Pressure is low compared with a hydraulic pack press but is applied evenly over a very large area, and the drum rotates between pressings to break the cake up and re-expose fresh surface.

Closed tank versions can be filled and worked under an inert gas blanket, giving the lowest oxygen pickup of any common press.

Open cage and closed tank

The open cage design has a perforated drum: juice leaves through the perforations directly into a tray beneath, and the whole surface of the cake is visible. It is simple, drains fast and is easy to inspect and wash out.

The closed tank design has a solid drum wall with internal drainage channels running its length, covered by a screen or mesh. Juice travels along these channels to a manifold and out through a single valve. Because the drum is sealed, the headspace can be flushed with carbon dioxide or nitrogen before and during pressing, so the juice barely meets air until it reaches the tank.

Both types work in cycles. The membrane inflates and holds, the operator or the programme releases it, the drum rotates a turn or two to tumble and break the cake, and the cycle repeats at a slightly higher pressure. A run is a sequence of such cycles, and it is the tumbling rather than the peak pressure that recovers the last of the juice.

What it does to the liquid

Low, even pressure extracts less of the harsh phenolic fraction and less fine solid than a high-pressure pack press. The juice is generally paler, cleaner and lower in suspended solids, and it settles more readily. For a maker aiming at a fresh, fruit-driven cider this is exactly the desired outcome; for a maker aiming at a heavily structured traditional cider it means phenolic extraction has to be recovered upstream, by maceration, or accepted as lower.

Oxygen pickup is low in the open cage version and very low in a gas-blanketed tank version. That preserves aroma compounds and colour, but it also means the juice arrives at the fermenter with its full phenolic complement unoxidised, which changes both the sulphiting decision and the tannin the finished cider will show.

The cake left behind is generally drier than a basket press leaves and comparable to a good rack and cloth run, though the balance between them depends heavily on mash preparation. Pneumatic presses handle a finer mash than a rack and cloth press will, and they handle a coarse one too, which is part of their appeal.

Practical considerations

They need a compressed air supply of adequate capacity, which is itself a piece of plant with its own maintenance and its own oil-carryover risk if the compressor is not the right type.
The membrane is a consumable. It perforates on a stone or a stray piece of metal, and replacing it is expensive.
Cleaning is easier than a rack and cloth press but not trivial: the drainage channels, the screens and the underside of the membrane all hold residue, and the manifold is a classic dead leg.
Cycle times are longer than a batch pack press for the same volume, because the process is deliberately incremental.

Compressed air is stored energy

A pneumatic press is a pressure system. Membranes, air lines, receivers and relief valves are safety-critical parts, and the manufacturer’s inspection and pressure-testing schedule is not optional. Never run a press with a defeated relief valve or a damaged membrane, and never open a drum before the membrane has fully vented.

Also answered on this page

Questions this page covers, so you can tell at a glance whether it is the one you want.

Is a pneumatic press better for cider?
Why is pneumatic press juice paler?
What is a tank press?

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 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.
Why is sulphite added to cider — Sulphur dioxide suppresses spoilage bacteria and wild yeast before fermentation and protects the finished cider from oxidation. How much of it is active depends strongly on pH, which is why low-acid juice is harder to protect.
Does cider contain antioxidants — Cider carries apple polyphenols, and tannic bittersweet ciders carry considerably more than pale ones made from dessert fruit. What that means for health is a clinical question this site does not adjudicate.
What is a bladder press — A bladder press inflates a rubber membrane inside a perforated cylinder, squeezing pomace outwards against the cage. It is gentle, quick to load and popular at small commercial scale.
Why does apple juice go brown when pressed — Polyphenol oxidase in the fruit reacts phenolics with oxygen the moment cells are broken, turning the juice brown. In cider making this is sometimes prevented with sulphite and sometimes encouraged, because it also drops harsh tannin out of solution.

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.
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.
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.

Where to go next

Cider making equipment — The rest of the equipment material, grouped by what each piece is for.
How cider is made — The methods this equipment exists to carry out.
Troubleshooting — The faults that are traced back to equipment and to cleaning.