Juice treatment
Patulin control
Managing the mycotoxin produced by rot fungi in damaged apples, which is controlled by fruit selection rather than by any treatment applied to juice.
Also called Mycotoxin management, Rot exclusion.
- Stage
- Juice treatment
- Traditional in
- No single tradition — used wherever it suits
- What it most changes
- Not recorded as moving a sensory dimension
- Safety
- Carries a safety consideration — see below
Patulin is a regulated mycotoxin and the only reliable control is excluding rotted and heavily bruised fruit before milling. It is heat-stable, so pasteurisation is not a remedy, and no fining or filtration treatment can be relied on to remove it. Risk is highest in unfermented juice, in fruit that has lain on the orchard floor, and in long-stored fruit where a rot has spread unnoticed. Producers should work to the limits and monitoring requirements in force in their own market, which differ between jurisdictions and are periodically revised, and should apply tighter control where the product is intended for children.
What it is
Patulin is a mycotoxin produced by several moulds that colonise damaged apples, most importantly Penicillium expansum, the blue-mould rot that spreads from bruises, punctures and stem-end wounds in stored and fallen fruit. It passes into juice when affected fruit is pressed, it is not destroyed by heat, and it is not removed by ordinary filtration or fining. Control is therefore overwhelmingly a matter of what goes into the mill, supported by the useful fact that alcoholic fermentation substantially degrades it. It is the principal chemical food-safety consideration in cider and juice production.
Why it is used
- Patulin is a recognised contaminant of apple products and is regulated in most markets, with limits set for juice and generally tighter limits for products intended for infants and young children.
- The contamination cannot be corrected downstream: heat does not destroy it, and pressing a single badly rotted apple can contribute a disproportionate load to a batch.
- The same fruit-selection discipline that controls patulin also controls mould taint and the earthy, musty aroma that rotted fruit contributes to a cider regardless of toxin content.
- For anyone selling unfermented juice, the control is critical, because the fermentation step that would otherwise degrade much of the toxin is absent.
How it works
- Penicillium expansum requires a wound to establish; sound, intact apple skin is a genuine barrier, which is why bruising during harvest and handling is the practical determinant of risk.
- Toxin production is concentrated in and immediately around the rotted tissue, so it extends beyond the visibly affected area but is not distributed evenly through an apparently sound fruit.
- Patulin is a small, heat-stable lactone. Pasteurisation and even more severe thermal processing reduce it only modestly, so no heat step can be treated as a control measure.
- Fermentation degrades it substantially: it reacts with thiol compounds, notably yeast-derived sulphhydryl groups, and is metabolised by Saccharomyces cerevisiae, so fermented cider generally carries far less than the juice it came from.
- Clarification and settling remove some patulin along with the solids, because a fraction is associated with particulate matter, but this is a partial reduction and not a control.
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
Organisms involved
Penicillium expansum
The blue mould of stored apples and the principal producer of patulin, the one genuine chemical safety issue that rotten cider fruit raises.
Botrytis cinerea
Grey mould: a broad-host-range fruit rot whose laccase enzyme oxidises phenolics and whose glucans make a juice difficult to clarify.
Monilinia fructigena
The brown rot of apples and pears, recognisable by concentric rings of buff pustules, and a major cause of fruit loss between the orchard and the mill.
Aspergillus species
A large genus of storage moulds, more important in warm climates than in northern cider regions, and a source of musty taint and of mycotoxins other than patulin.
Saccharomyces cerevisiae
The yeast that finishes essentially every cider, whether it arrives in a sachet or from the fruit, the press and the vessel.
What it is done with
The apple washer and the flotation tank
Cider fruit is gathered off the orchard floor, so it arrives with soil, grass, stones and rot attached; a flotation tank separates the fruit from the stones by density alone, and a spray or brush stage takes off what floating will not.
Laboratory measurement versus practical measurement
Gravity, temperature, pH and total acidity are all within reach of a careful person with modest equipment; alcohol by volume, sulphur dioxide for a declaration, patulin, methanol and microbiological counts are not, and pretending otherwise is how numbers on labels become wrong.
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.
Patulin contamination
Contamination of juice or cider with patulin, a mycotoxin produced by Penicillium expansum in rotting apples — a genuine food-safety question rather than a flavour one.
Mould taint
Musty, earthy, cellar-damp or rotten-fruit character carried in from mouldy fruit or from mouldy equipment, and a marker that the patulin question needs asking.
More on patulin control
The essential shape of this problem is that the toxin is created in the orchard and the store, not in the cellar, and nothing done in the cellar removes it. Penicillium expansum is ubiquitous, its spores are on the fruit and in the air of every fruit store, and it needs only a wound to get in. A bruise from a drop onto hard ground, a puncture from a stem, a split from frost or from a wasp — any of these is an entry point, and once established the rot spreads through the fruit producing toxin as it goes. Fruit that has lain on the orchard floor for weeks, particularly in a wet autumn, is the highest-risk material there is, and it is also, historically, exactly what a great deal of traditional cider was made from.
That historical point deserves an honest treatment rather than an anxious one. Traditional practice of gathering windfalls and letting them lie was developed before mycotoxins were known about, and it persists in places. Two things moderate the risk in traditional cider: the fruit was fermented rather than drunk as juice, and fermentation degrades patulin substantially through reaction with yeast thiols and yeast metabolism. That is a real and well-described effect, and it means fermented cider is a lower-risk product than unfermented juice from the same fruit. It is not a licence to press rot, because the degradation is partial, because the mould taint remains regardless, and because the same fruit brings other spoilage with it.
The controls, in order of effectiveness, are: pick fruit rather than let it lie, or if gathering from the ground do it promptly and often rather than in one late sweep; sort on an inspection table or belt, and cut out or discard fruit showing soft brown rot rather than trimming it optimistically; wash, which removes surface spores and soil but does not touch toxin already inside the fruit; and keep stored fruit cool, dry and inspected, since a store is where a small rot becomes a large one. Millers and elevators that bruise fruit heavily create the wounds that the next fortnight’s rot will exploit, so handling gentleness in the yard matters as much as vigilance at the sorting table.
The regulatory position is settled in principle and variable in detail. Limits exist for apple juice and apple products in most major markets, with lower limits for products intended for infants and young children, and monitoring expectations sit alongside them. The numbers differ between jurisdictions and are revised, so a producer needs the current figures for their own market rather than a remembered one. What does not vary is the control strategy: this is a hazard managed at the point of fruit intake, by people looking at fruit and rejecting what is not sound, and every other measure in the chain is secondary to that.
Related processes
Steps that sit alongside this one, replace it, or depend on it having been done.
Harvest
Fruit sorting
Taking rotten, mouldy and damaged fruit and foreign material out of the crop before it reaches the mill, which is the primary control on patulin in cider.
Harvest
Windfall management
Deciding which fruit that has reached the orchard floor can be used, and getting the rest out of the crop before it becomes a patulin problem.
Fruit preparation
Fruit washing
Removing soil, grass, stones and surface contamination from gathered fruit, usually in a water flume, before it reaches the mill.
Harvest
Fruit storage before milling
Holding a gathered crop between harvest and the mill, and managing what respiration, water loss and spoilage do to it while it waits.
Juice treatment
Juice pasteurisation
Heat treatment of juice before fermentation, which inactivates enzymes and microorganisms, and in doing so removes the wild flora that would otherwise ferment it.
Juice treatment
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
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 do i sterilise cider bottles — Wash them clean first, then sanitise with a no-rinse sanitiser or a sulphite solution, and fill while still wet with it. Bottles that look clean but have dried deposits inside are the usual source of bottle spoilage.
- Which yeast ferments cider — Saccharomyces cerevisiae finishes almost every cider fermentation, whether it was pitched or arrived from the press house. In a spontaneous ferment it is not the first organism present, only the one that survives the alcohol it makes.
- Can you use windfall apples for cider — Traditional cider making relies on fruit gathered from the ground, and there is nothing wrong with it if it is sound. Rotten fruit is a different matter: brown rot carries patulin into the juice and should be discarded, not pressed.
- How long can apples be kept before pressing
- Will pasteurised apple juice ferment — Not on its own — pasteurisation kills the wild yeast — but it ferments readily once a cultured yeast is pitched.
- Which measurements can i do myself and which need a laboratory
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.
European Food Safety Authority scientific opinions
EFSA · regulator · retrieved 2026-08-24
Registered for the food-safety questions cider genuinely raises: patulin in juice from rotten fruit, sulphite sensitivity, and the toxicology behind additive limits.
Codex Alimentarius food standards
FAO / WHO · standards body · retrieved 2026-08-24
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.