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.
Also called Mash enzyming, Pomace pectinase, Maceration enzymes.
- Stage
- Fruit preparation
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Body down, phenolic character up
- Safety
- Carries a safety consideration — see below
Enzyme preparations are proteins, and inhaled dust or aerosol from powdered products is a recognised respiratory sensitiser: handle granular products in a way that avoids raising dust, and follow the supplier’s handling guidance. Dose according to the manufacturer’s specification for the fruit and temperature rather than by eye, and confirm before use that the preparation is permitted for your product and jurisdiction — several designation schemes restrict processing aids.
What it is
The application of a commercial pectolytic preparation to pomace between the mill and the press, so that the enzyme works on the intact cell-wall structure of the fruit rather than on the soluble pectin already in the juice. The preparations are fungal in origin, sold as liquids or granules, and formulated for this job specifically — mash or maceration enzymes as distinct from the clarification enzymes used after pressing. The purpose is mechanical rather than cosmetic: a pomace whose pectin network has been partly dismantled holds less water, drains faster and gives up more of its juice at a given pressure.
Why it is used
- Press yield is a direct cost line in any volume operation, and treating the pomace recovers juice that would otherwise leave in the cake.
- A pomace that drains readily allows shorter press cycles, which raises throughput on the same equipment during the short harvest window.
- Fruit that has been held too long, or that mills to a slippery pulp, can be almost unpressable in a belt or bladder press, and enzyme treatment restores workable drainage.
- Treating at the pomace stage also degrades pectin that would otherwise reach the juice, so the later clarification job is smaller.
How it works
- Pectin in the middle lamella is a galacturonan backbone whose carboxyl groups are partly esterified with methanol; the network holds water and gives the pomace its jelly-like resistance to drainage.
- Pectin methylesterase removes those methyl esters, releasing methanol and leaving free carboxyl groups that can be bridged by calcium — the reaction that makes keeving possible, and the reason PME on its own gels rather than liquefies.
- Polygalacturonase hydrolyses the de-esterified backbone between galacturonic acid units, cutting the polymer into fragments and collapsing the water-holding network, which is what actually releases the juice.
- Pectin lyase cleaves the still-esterified backbone by a β-elimination mechanism, so it works on highly esterified apple pectin directly and, unlike the PME plus polygalacturonase route, liberates no methanol.
- Mash preparations usually carry accessory arabinanase and hemicellulase activity, because arabinan side chains released by pectin degradation are themselves a cause of haze that appears after the juice has apparently been clarified.
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 | Depolymerising the pectin removes the colloidal fraction that contributes viscosity and a soft mouth-coating texture, so a thoroughly enzymed juice ferments to a leaner cider than the same fruit pressed untreated. |
| Phenolic character | Raises | Breaking down cell walls releases phenolic material bound in the skin and in the tissue immediately beneath it, so more procyanidin reaches the juice than free-run pressing would have delivered. |
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 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.
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.
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.
Arabinan
The branched neutral sugar side chains of pectin, which can be liberated intact by pectinase treatment and then form a haze that appears weeks after the juice looked perfectly clear.
Methanol
A small alcohol released not by fermentation but by enzymes stripping methyl groups off pectin, which is why juice handling rather than yeast choice governs how much a cider contains.
Calcium pectate
The gel formed when calcium bridges de-esterified pectin chains, which floats to the surface as the brown cap of a keeve and carries the juice’s nutrients out with it.
What it is done with
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.
Pectin haze
A persistent, slightly viscous haze that will not settle, caused by pectin from the fruit remaining in solution as a colloid.
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.
More on enzyme addition to pomace
The single most important thing to say about pomace enzyming is that it is incompatible with keeving, and not marginally so. Keeving depends on the fruit’s own pectin methylesterase de-esterifying the pectin slowly and gently, so that the free carboxyl groups can be bridged by calcium into a pectate gel which traps particles and yeast and floats to the surface as the chapeau brun. A commercial mash enzyme carries polygalacturonase and pectin lyase activity that cuts the galacturonan backbone into fragments too short to form a coherent gel; once that has happened no amount of calcium will build a brown cap, and the nutrient stripping that keeving exists to achieve cannot occur. A maker cannot enzyme the pomace for yield and then keeve the juice. The two techniques answer different questions — one asks for maximum extraction, the other for deliberate impoverishment — and the choice has to be made at the mill.
The two enzymatic routes to depolymerisation are not equivalent in what they leave behind. The PME plus polygalacturonase route de-esterifies first and then cuts, and the de-esterification step releases methanol stoichiometrically from the methyl esters — a normal constituent of all fruit juices and ciders, but one whose concentration rises with the extent of pectin de-esterification. Pectin lyase avoids the step entirely by cleaving the esterified polymer directly, which is one reason lyase-rich preparations are favoured in modern juice technology, and why German juice-technology guidance discusses the choice in these terms. Neither route touches starch: a juice hazy with unconverted starch from early-picked fruit needs amylase, and a maker who doses pectinase at the mill and still sees a haze that gives a blue-black iodine reaction has diagnosed the wrong polymer.
What varies between traditions is less the chemistry than whether the technique is used at all. Large-volume production in Britain, Germany and North America uses mash enzymes as a matter of routine, because yield and throughput dominate the economics and the resulting juice is going into a filtered, clarified product where the lost colloidal body would have been removed anyway. Traditional French cidre production, and anything keeved, excludes it by necessity. Sidra natural producers working with a wild ferment and a cloudy, unfiltered product have less to gain and a texture to lose. Overdosing is the common technical error: a pomace enzymed hard gives excellent yield and a thin, over-extracted juice that has pulled more skin phenolic and more cell-wall debris into the press than the maker wanted, and the cider that results can be simultaneously more astringent and less substantial than the untreated equivalent.
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.
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.
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.
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
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.
- How are apples milled for cider
- 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.
- 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.
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.
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.