Comparison
Sulphited vs unsulphited
Why is sulphite added to cider, and what happens if it is not?
In short
Sulphur dioxide does two jobs. In its molecular form it inhibits bacteria and non-Saccharomyces yeasts, and its effectiveness depends steeply on pH — the lower the pH, the more of the added sulphite exists in the active molecular form. It also binds acetaldehyde and inhibits the enzymes that drive browning.
Working without it is entirely possible and is traditional in several regions, but the protection has to come from somewhere else: scrupulous hygiene, a low enough pH, cool fermentation, full vessels and timely racking. Spanish, Basque and much traditional English farm practice runs this way.
The cost of omitting sulphite is a wider range of outcomes — more oxidative and phenolic character, and a greater chance of a spoilage organism establishing. The cost of using it is that it suppresses the mixed population a wild ferment depends on, and that above a threshold it must be declared on the label.
The two things being compared
Each side described in its own terms first, so the table below has something to hang on.
Sulphited cider
Sulphur dioxide added at pressing, after fermentation or at bottling to suppress spoilage organisms and limit oxidation.
Unsulphited cider
No added sulphur dioxide. Protection comes from hygiene, pH, temperature and vessel management instead.
Where they differ
Dimension by dimension. Where a row needs a qualification, it carries one rather than being simplified until it fits.
| Dimension | Sulphited cider | Unsulphited cider |
|---|---|---|
| Microbial suppression | Direct, and strongly pH-dependent. | Indirect, through hygiene, cool temperatures and low pH. |
| Oxidation | Binds acetaldehyde and inhibits browning enzymes. | Oxidative development proceeds, which is a fault in some styles and a defining feature in others. |
| Effect on wild fermentation | Suppresses the non-Saccharomyces population the succession depends on. | Leaves it intact. |
| pH sensitivityThis is why an unsulphited cider from low-acid bittersweet fruit is a harder proposition than one from sharp fruit. | A dose that protects a low-pH juice may do very little at high pH. | High pH is a risk with or without sulphite, but the fallback options are fewer. |
| Labelling | Must be declared above the regulated threshold. | No declaration, though small amounts arise naturally in fermentation. |
| Variability of outcome | Narrower. | Wider, in both the interesting and the unwelcome directions. |
| Where each is standard | Commercial production almost everywhere, and much small-scale practice. | Asturian and Basque sidra natural, and a portion of English farm and French fermier production. |
Notes under a dimension name qualify the whole row, not one column.
The numbers around sulphite
Sulphite only protects in its molecular form, and how much of a free sulphite reading is in that form depends almost entirely on pH. At pH 3.0 about one part in sixteen is active; at the pH of a typical bittersweet juice, around 4.1, it is one part in two hundred. That single relationship explains why sharp-fruit cider traditions could rely on sulphite and bittersweet ones relied on cold, clean vessels and a fast-starting yeast instead.
Unsulphited cider is not a fringe practice. The best-documented spontaneous ferments on this site, in Asturian cellars, ran without any sulphite at 12–15 °C and finished sound; the cold, and a juice too low in sugar to reach a high alcohol, did the protecting. Where sulphite is used, the limits are written into specifications rather than left to habit, and above 10 mg/L it must be declared on the label.
| Figure | Source | |
|---|---|---|
| Active share of free SO₂ at pH 3.0 | About 6% | Dissociation of sulphurous acid |
| At pH 3.5 | About 2% | The same |
| At pH 3.8 | About 1% | The same |
| At pH 4.1 | About 0.5% | The same |
| Declared as an allergen above | 10 mg/L total SO₂ | EU and retained UK food-information rules |
| Three Counties cider and perry | Total under 200 mg/L; free 40–60 mg/L | PGI specifications |
| Traditional Welsh Perry | Up to 200 mg/kg | PGI specification |
| Sidra de Asturias, sparkling | Total under 200 mg/L | DOP specification |
- Molecular SO₂ — what a measured free SO₂ figure amounts to at your juice’s pH.
- Juice analysis interpreter — where your juice’s pH sits among the measured juices.
When Sulphited cider is the relevant one
The circumstances in which this is the thing being described, rather than a reason to prefer it.
- The juice is high in pH or the fruit was poor, and the ferment needs protection.
- The cider must survive distribution with residual sugar or without pasteurisation.
When Unsulphited cider is the relevant one
The circumstances in which this is the thing being described, rather than a reason to prefer it.
- The tradition being described works without it, as Asturian and Basque practice does.
- A wild ferment is intended and the resident population must survive.
- You are explaining why a cider shows pronounced oxidative or phenolic character.
A misconception worth clearing up
This comparison exists partly because of the claim below, which is repeated often enough that most readers arrive holding it.
Sulphites in cider are what cause hangovers and headaches.
What is actually the case: Sulphite sensitivity is a real but uncommon reaction, most clearly documented in people with asthma, and it presents as respiratory symptoms rather than headache. The evidence does not support sulphite as a general cause of hangover, which is driven principally by ethanol itself.
Related comparisons
Distinctions that turn on the same thing, or that this one is routinely confused with.
Wild vs cultured fermentation
A wild ferment runs on the yeasts already present on the fruit and in the building; a cultured one is started with a selected strain in sufficient quantity to dominate from the beginning.
Pasteurised vs unpasteurised
Pasteurisation uses heat to kill the organisms that would otherwise continue changing the cider in the package; leaving it out keeps the cider alive, and with it both the potential to develop and the potential to spoil.
Oxidation as fault vs oxidation as style
Controlled slow oxidation during maturation develops colour, softens tannin and adds complexity; uncontrolled oxidation strips fruit aroma, browns the cider and pushes it towards acetaldehyde and vinegar.
English vs Spanish cider traditions
Two complete traditions with different premises: the English builds structure from tannic fruit and manages sweetness and carbonation; the Asturian and Basque build acidity and wild-ferment character and animate the drink at the moment of pouring.
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 the difference between wild and cultured fermentation in cider — A wild fermentation is carried by the yeasts already on the fruit and in the press house, in a succession of species; a cultured one is started by pitching a single chosen strain. Wild ferments are slower, more variable and can carry aromas a single strain does not make.
- Why is spanish cider so different from english cider — Asturian and Basque cider is fermented dry, is usually not carbonated, and is poured from a height to aerate it in the glass. English cider is more often sweetened, more often carbonated and rarely poured that way, and the two traditions use different fruit and different classification systems.
- Does pasteurising cider change the way it tastes — Pasteurising stops fermentation and microbial change permanently, which secures a sweetened cider against refermenting. It also fixes the cider as it was on the day, so it will not develop further in bottle.
- When is oxidation in cider a fault
Where to go next
- All comparisons — The rest of the pairs, grouped by what kind of difference is at stake.
- Glossary — Either term on its own, defined without a second thing to hold it against.
- Learn about cider — The background these pages assume, written from the beginning.
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 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.
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.
Regulation (EU) No 1169/2011 on the provision of food information to consumers
European Union · legislation · passage verified 2026-08-24
The instrument behind the "contains sulphites" declaration and the alcoholic-strength labelling rule. Read on 2026-08-24 in the assimilated text maintained on legislation.gov.uk, which is the version in force for Great Britain and keeps the EU numbering. Two provisions matter to cider and both are widely misquoted: the sulphite threshold is 10 mg/L rather than a percentage, and a labelled cider strength carries a tolerance of a full percentage point either way — twice what still grape wine is allowed.
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.
UK protected geographical food and drink names register
Department for Environment, Food and Rural Affairs · government · passage verified 2026-08-25
The register itself is an index; the substance is in the product specification attached to each entry as a PDF. Eight cider and perry specifications were downloaded and read on 2026-08-24 — the six Three Counties names and the two Welsh ones. Reading them settled a question CiderHQ had previously described in the abstract and got wrong: the Three Counties specifications state a composition table, not a minimum juice content. The Traditional Welsh Perry specification was re-read on 2026-08-25 for the comparison with Austrian fruit-wine law, and its prohibition list transcribed in full: the two instruments turn out to regulate opposite things, one composition and one technique.
Consejo Regulador de la DOP Sidra de Asturias; Gobierno del Principado de Asturias · designation authority · passage verified 2026-10-08
The designation’s specification itself, read in full on 2026-10-08 in the regulating council’s copy (eighteen pages, dated September 2025) and compared with the Principality’s copy, whose text is identical. The address first recorded for the Principality’s copy returns 404. The specification gives analytical limits for sidra natural as well as for the sparkling category, lists what may not be added, and contains no ban on filtration.
Yeast species associated with the spontaneous fermentation of cider
Suárez Valles, Pando Bedriñana, Fernández Tascón, Querol Simón and Rodríguez Madrera, Food Microbiology 24(1):25–31 · peer-reviewed literature · passage verified 2026-08-24 · covers 2001–2002
SERIDA’s survey of what is actually growing in an Asturian cellar during a spontaneous ferment, across two harvests and two pressing technologies. Read in full from the author institution’s open repository (ria.asturias.es, handle 123456789/925) on 2026-08-24. Two things make it worth citing rather than summarising: it identifies its isolates molecularly rather than by colony appearance, and it publishes the analytical composition of the finished ciders alongside the microbiology, so a reader can see the organisms and the numbers they produced in the same paper. It also contradicts the textbook account of apiculate yeasts dying out early, which is why CiderHQ cites it on that point specifically.