Fault
Starch haze
A persistent haze caused by starch carried in from under-ripe fruit, which has not yet been converted to sugar and stays suspended in the cider.
Also called starch cloud, unripe fruit haze.
- Severity
- Cosmetic — looks wrong, tastes fine
- Where it starts
- Harvest, Orchard, Fruit preparation
- Can it be fixed?
- Yes, if caught in time
- When you notice it
- Pressing, Juice treatment, Fermentation
- Signs
- 5 recorded
What it is
Starch haze comes from fruit that was pressed before it was ready. Apples store carbohydrate as starch during growth and convert it to sugar as they ripen; fruit picked too early carries starch through into the juice, where it is not fermented, does not settle and produces a haze that resists ordinary clarification. It is entirely preventable at harvest, and it is one of the reasons the starch-iodine test exists.
What you notice
Grouped by sense, because that is how the fault presents itself rather than how it works.
To look at
- A pale, milky haze that persists through fermentation and racking
How the batch behaves
- Haze in a cider from an early-picked or early-season crop
- A cut apple from the same batch staining blue-black with iodine solution — The definitive test, and it is done on the fruit before pressing rather than on the cider afterwards.
- Juice that was noticeably low in gravity for the cultivar — Starch not yet converted is sugar not yet present.
On the palate
- A thin, green, slightly hard character in the finished cider
The words for it: Unripe apple. Each links to what produces it.
When it appears. From the press, where under-ripe fruit was used, and it persists. Like a pectin haze it does not develop in a cider that was previously clear.
It is a direct consequence of pressing before starch conversion was complete, which makes it the one haze that carries information about the fruit rather than about the process. The starch-iodine test used to judge ripeness in the orchard is the same test used to diagnose it in the vessel.
Claude Jolicoeur, Chelsea Green Publishing, 2013. ISBN 9781603584739, Cornell University, School of Integrative Plant Science
What it is mistaken for, and how to tell
One observation per rival, chosen because it separates them rather than because it describes either. Several of these are not faults at all — a style feature, a normal outcome, or the fruit behaving as it does.
- Pectin haze — The iodine test settles it in seconds: blue-black is starch, no change is pectin.
- A haze from unripe fruit that is otherwise fine — These are the same thing. The haze is a marker of under-ripeness, and the more useful finding is usually what else the unripe fruit cost — sugar, and softened phenolics.
What is actually happening
The chemistry or microbiology behind it. Understanding the mechanism is what makes the prevention make sense rather than being a list of rules.
Apple fruit accumulates starch granules in the cortex through the growing season and hydrolyses them to sugars as it approaches maturity, under the control of amylases active during ripening. The starch-iodine test exploits the fact that iodine forms a deep blue-black complex with amylose; a cut face that stains heavily is starchy, and one that stains only near the core is ready.
Starch that reaches the juice is a polysaccharide that yeast cannot ferment. It remains in suspension as fine particles and as a partly gelatinised colloid, scattering light. Neither fermentation nor racking removes it, and because the particles are small the cider does not clear on standing.
Amylase preparations hydrolyse starch to fermentable sugars and dextrins and will clear the haze. They are a different class of enzyme from pectinase, and a pectolytic preparation will not touch starch — which is why treating a starch haze with pectinase produces no result and confuses the diagnosis.
Storing fruit before milling addresses the same problem at source. Apples continue to ripen off the tree, converting starch to sugar, which is the underlying reason for the traditional practice of sweating the fruit in heaps before pressing.
How it happens
| Cause | Stage | How often |
|---|---|---|
| Fruit picked before it was physiologically ripe | Harvest | common |
| A whole crop pressed on one convenient day regardless of the fruit’s state | Harvest | common |
| Early-season cultivars pressed at their earliest usable point | Harvest | occasional |
| A cool season in which the crop did not finish ripening on the tree | Orchard | occasional |
| No fruit storage or sweating period before milling | Fruit preparation | occasional |
| Windfalls from a summer storm pressed with the main crop | Harvest | occasional |
Can it be put right?
Most cider faults cannot be reversed. Where that is the answer it is given plainly — an honest 'this batch is what it is' is more useful than a procedure that will not work.
| Option | Effectiveness | What it involves |
|---|---|---|
| Pick later next season | Reliable | The real answer. Starch haze is a harvest decision showing up in the glass six months later, and no treatment is as effective as leaving the fruit alone for another fortnight. |
| Treat the cider with an amylase preparation | Partial | The correct enzyme for the problem, and it works. Use the supplier’s rate and temperature guidance; activity falls in the presence of ethanol and at cellar temperature. |
| Filter it out | Partial | Possible, with more filter media than the volume warrants, and the finest fraction may still pass. Enzyme treatment first makes it far easier. |
| Wait for it to settle | Unlikely to work | Some coarse starch settles over a long period; the fine fraction does not, and the cider stays hazy. |
| Treat with pectinase | Not possible | Pectolytic enzymes do not hydrolyse starch. This is the commonest wasted intervention on a starch haze. |
CiderHQ gives no additive dosage figures. An addition is a food-safety decision that depends on legal limits, on the juice in front of you and on what you are protecting against, and the right figure comes from your supplier’s or regulator’s own guidance rather than from a general reference.
Preventing it
- Test fruit with iodine solution before pressing rather than judging ripeness by colour or by the calendar.
- Store fruit in heaps or crates for a period before milling so it can finish converting starch, which is what sweating the fruit is for.
- Press cultivars as they come ready rather than on a single date for the whole orchard.
- Judge ripeness by several indicators together — seed colour, ease of separation, juice gravity — not by one.
- Keep obviously unripe windfalls out of the press.
Starch haze is a harvest fault wearing a cellar fault’s clothes. Everything about it is decided before the fruit reaches the mill, and by the time the haze is visible the decision that caused it is many months in the past.
It is also a useful reminder of what ripeness means for cider fruit. A cider apple is ready when its starch has become sugar, and that point is later than the point at which it looks ready, comes off the tree easily or drops. The iodine test is a two-minute procedure that answers the question directly, and it is one of the highest-value habits a small producer can adopt.
The traditional practice of sweating fruit in heaps before pressing is doing exactly this work. The fruit softens, respires, loses a little water and converts residual starch to sugar; the juice is sweeter, the gravity higher, and the starch problem has gone away without anyone adding anything.
The associated flavour cost is worth noting alongside the haze. Fruit pressed short of ripeness gives lower gravity, higher acid and a green, hard character, so a starchy juice is usually a thin cider as well as a cloudy one. The haze is the visible part of a larger loss.
The compounds involved
Starch
The fruit’s carbohydrate store, unfermentable until ripening converts it to sugar, and the reason picking early costs alcohol and risks a haze that will not clear.
Glucose
The sugar yeast takes first and the smallest of the three in apple juice, which is why the last sugar left in a slow ferment is almost never glucose.
Sucrose
The disaccharide of apple juice and the sugar most often added to it, split into glucose and fructose by the yeast’s own invertase before any of it is fermented.
Sorbitol
The unfermentable sugar alcohol that pears carry in quantity and apples carry only in trace, and the single reason a fully fermented perry keeps a sweetness a fully fermented cider cannot.
Where in the process it arises
Ripeness assessment
Judging when cider fruit has converted enough starch, loosened enough on the spur and hardened enough for the store to be worth gathering.
Starch–iodine testing
Staining a cut apple with iodine solution so that remaining starch turns blue-black, giving a visible map of how far conversion to sugar has progressed.
Sweating the fruit
Deliberately heaping or storing gathered fruit so that it softens, loses water and finishes converting starch before it goes to the mill.
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.
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.
Filtration
Passing cider through a porous medium to reach a stated visual brightness, at a real cost in colloidal material, body and aroma.
Faults it is confused with
These present similarly. What separates them is set out on each page.
Pectin haze
A persistent, slightly viscous haze that will not settle, caused by pectin from the fruit remaining in solution as a colloid.
Thin body
A cider with no weight or texture in the mouth, most often from over-watered pomace, low-gravity juice or a blend with nothing to give it substance.
Excessive acidity
Acidity high enough to dominate everything else, leaving a cider that is thin, hard and sour rather than fresh.
Protein haze
A fine haze that forms as protein and tannin combine into insoluble complexes, often appearing in a cider that had already been clear.
Where this comes up in a guide
The link lands on the step where the fault arises rather than at the top of the pathway, because that is where the decision that causes it is taken.
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 clear a cloudy cider
- When are cider apples harvested — In the northern hemisphere the cider harvest runs from about September to November, with late bittersweets such as Dabinett and Vilberie coming in last. Cider fruit is generally picked riper than dessert fruit, and often gathered from the ground.
- Why is sorbitol important in perry — Sorbitol is a sugar alcohol that pears carry in quantity and that Saccharomyces cannot ferment. It passes through the whole fermentation untouched, so a perry can taste sweet while being dry by measurement.
- Why is my cider so sharp
- Why is my cider thin and watery — Thin body usually follows from dessert-fruit juice with little tannin, over-dilution, aggressive filtration, or a ferment that stripped everything out. Body in cider comes mostly from tannin, glycerol and residual sugar.
- 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.
Where to go next
- The fault finder — Describe what you can smell and see, and narrow it down from the signs.
- All faults — Grouped by where they come from and how serious they are.
- Cider science — The chemistry and microbiology these faults come out of.
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.
A Somerset Pomona: The Cider Apples of Somerset
Liz Copas, The Dovecote Press, 2001. ISBN 9781874336877 · reference work · bibliographic record verified, not opened 2026-08-25
Bibliographic record verified on 2026-08-25 against Open Library: Liz Copas, The Dovecote Press, 2001, ISBN 9781874336877. The author was Long Ashton’s cider pomologist, which is why this work is registered for Somerset cultivar identity at all — it is the nearest thing to a successor to the station’s own descriptions. No copy was opened. Not digitised in any open collection.