Equipment
Particle size, yield and phenolic extraction
How finely should apples be milled?
In short
Two opposing effects govern milling. Finer particles mean more ruptured cells and more accessible juice, but they also mean a mash that packs tight under pressure and blinds its own drainage paths.
The optimum is therefore not a property of the fruit; it is a property of the press. A rack and cloth or basket press wants coarse, structured pomace. A belt or pneumatic press with enzyme treatment can handle a much finer mash and turn the extra cell rupture into real yield.
Particle size also sets how much phenolic material and how much oxidation the juice inherits, because both scale with the surface area created.
Why finer is not simply better
Juice does not leave pomace by being squeezed out of individual cells so much as by flowing through channels between particles. A cake of coarse chunks is full of such channels and stays full of them as pressure rises, because the chunks bridge against each other. A cake of fine pulp has channels only until pressure closes them; then the mash behaves as a viscous liquid trapped in a sealed bag, and further pressure achieves nothing except deforming the press.
The failure mode is recognisable: pressure on the gauge rises, flow at the outlet stops, and releasing the pressure produces a brief further run as the cake relaxes. This is why traditional practice builds a cheese in thin layers separated by racks — it is manufacturing drainage paths that the pomace itself no longer provides.
Fine particles also carry more fine solid into the juice. A juice full of pulp fines takes longer to settle, needs more enzyme or centrifugation, and gives a heavier, less clean gross lees at the first racking.
Phenolics and colour
Phenolic compounds in apples — procyanidins above all, along with chlorogenic acid and phloridzin — sit largely in the skin and in the cells near it. Getting them into the juice requires breaking those cells and giving the liberated compounds time and liquid to dissolve into. Finer milling does both: more cell rupture, more surface area, faster diffusion.
The same exposure accelerates enzymatic browning. Polyphenol oxidase is released along with its substrates, and in the presence of air converts them to quinones which condense into brown polymers. Some of that material is later lost with the lees, so heavy oxidation at the mill can actually reduce the phenolic content of the finished cider even though it raised the phenolic extraction at the press. This is a real and often-missed distinction: extraction and retention are not the same quantity.
A maker who wants tannin and is prepared to accept colour can mill finer and macerate. A maker who wants a pale, fresh, low-tannin cider mills coarser, presses promptly, and may protect the juice with sulphur dioxide or an inert gas at the mill outlet.
Rules of thumb worth distrusting
Published guidance on particle size is thin, and most of what circulates is stated as a screen aperture without saying what press it is for. That is close to meaningless: the same screen produces a workable mash on a horizontal pneumatic press and an unworkable one on a hand-built cheese.
The practical approach is empirical and cheap. Mill a small quantity at the settings available, build a small pack, press it, and see whether it flows. The signal to watch is not the yield figure but whether flow continues as pressure rises. If it stops early, go coarser. If the cake comes out wet and the press never had to work, go finer.
Where yield figures are quoted for a mill and press combination, they should always be read with the fruit condition attached. Ripe, sound, well-conditioned fruit yields more than green or frosted fruit at any particle size, and the difference is larger than the difference between milling settings.
Comparing the two directions
| Property | Coarser mill | Finer mill |
|---|---|---|
| Cell rupture and accessible juice | Lower | Higher |
| Drainage through the cake | Free | Poor without racks, cloths or enzyme |
| Realised yield on a traditional press | Good | Often worse than coarse, despite more accessible juice |
| Realised yield on a belt or pneumatic press | Moderate | Good |
| Phenolic extraction into juice | Lower | Higher |
| Rate of enzymatic browning | Slower | Faster |
| Suspended solids in the juice | Lower | Higher |
| Pectin released into the juice | Lower | Higher |
Also answered on this page
Questions this page covers, so you can tell at a glance whether it is the one you want.
- How fine should apple pomace be?
- Why did my press stop giving juice?
- Does milling affect tannin in cider?
Related
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.
- 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 are apples milled for cider
- 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 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 enzymatic browning
- What is maceration in cider making — Maceration is letting milled pomace stand before pressing, so that enzymes soften the tissue and phenolics and aroma move from the skins into the juice. It raises both colour and tannin, and raises the risk of oxidation with them.
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 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.
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.
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.
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.