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What wild fermentation is
Is wild fermented cider better?
In short
Wild or spontaneous fermentation means letting the yeasts already present on the fruit, on the equipment and in the building do the work, instead of adding a cultured strain. It is the older method and remains the norm in traditional Asturian, Basque, Norman and West Country practice.
It produces a more complex result. A spontaneous ferment begins with a succession of non-Saccharomyces yeasts that generate compounds a single cultured strain does not, before Saccharomyces cerevisiae takes over as the alcohol rises.
It is not reliably better. The same openness that produces complexity also admits spoilage organisms, and spontaneous ferments stick, acetify and develop off-characters more often than inoculated ones. Whether the trade is worth making depends on what the cider is meant to be.
Described in full
- Shape
- Two stacked bar charts one above the other, each with four bars. Bars are sampling days 1, 4, 16 and 28 after pressing. Each bar is divided into three segments summing to 100 per cent, and every segment carries its own percentage as a number so the reading does not depend on seeing the fill.
- What is counted
- The share of identified yeast isolates belonging to each group, not the number of cells. A group at 100 per cent was the only thing cultured from that sample; it does not mean nothing else was alive.
- The three groups
- Apiculate yeasts are Hanseniaspora valbyensis, H. uvarum and H. osmophila. Oxidative non-Saccharomyces are Metschnikowia pulcherrima and Pichia guillermondii. Saccharomyces is S. bayanus and S. cerevisiae together.
- Upper chart, pneumatic pressing
- Day 1: apiculate 84, oxidative 16, Saccharomyces 0. Day 4: apiculate 4, oxidative 10, Saccharomyces 86. Day 16: Saccharomyces 100. Day 28: apiculate 38, Saccharomyces 62. This is the textbook succession — non-Saccharomyces first, then a Saccharomyces takeover — except for the tail, where an apiculate yeast comes back at more than a third of isolates.
- Lower chart, traditional pressing
- Day 1: apiculate 66, oxidative 14, Saccharomyces 20. Day 4: apiculate 48, oxidative 4, Saccharomyces 48. Day 16: apiculate 90, Saccharomyces 10. Day 28: apiculate 94, Saccharomyces 6. Here the succession does not happen. Saccharomyces is present from the first day, never dominates, and the ferment finishes overwhelmingly apiculate.
- Why it matters
- Both ferments completed. Both gave dry cider of 6.4 to 6.5 per cent alcohol. The difference between them was how the fruit was pressed, and the account of cider fermentation as a fixed sequence of organisms does not survive it. Apiculate yeasts are usually described as dying out within days under rising alcohol; at 12 to 15 degrees Celsius, without sulphite, and on a must under 110 grams of sugar per litre, one of them ran the whole ferment.
- What this is not
- One cellar, one harvest, four ferments. It is evidence that the succession varies, not a measurement of how often it varies this way.
What is actually in the vessel
Freshly pressed juice carries a substantial and varied microbial population. Apple surfaces carry apiculate yeasts — Hanseniaspora and Kloeckera species — along with Metschnikowia, Candida, Pichia and Torulaspora, and the mill, press, hoses and vessels carry a resident population built up over years of use. Saccharomyces cerevisiae is often barely detectable on the fruit itself and arrives largely from the equipment and the building.
For the first days the apiculate yeasts dominate. They ferment relatively slowly, tolerate only a few percent alcohol, and produce esters, higher alcohols and glycerol in proportions that differ from what Saccharomyces produces. Much of the aromatic distinctiveness attributed to wild fermentation is generated in this early phase.
As alcohol rises past roughly 4%, the apiculate yeasts die back and Saccharomyces takes the ferment to completion. Lactic acid bacteria may follow, converting malic acid to lactic acid; acetic acid bacteria will follow too if oxygen is available. This sequence is what microbiologists call the succession, and it is the defining feature of a spontaneous ferment.
Wild, inoculated and the ground in between
| Approach | How it starts | What it gives | What it risks |
|---|---|---|---|
| Fully spontaneous | Nothing added; the resident population takes over | Full microbial succession; the widest range of aroma compounds; the character of a particular place and building | Slow or failed starts, stuck ferments, acetification, mousiness, and batch-to-batch variation |
| Pied de cuve | A small volume of juice is fermented first and used to inoculate the main batch | A wild population, but a vigorous and selected one, starting fast enough to outcompete spoilage | Still wild, so still variable, and the starter itself can be faulty |
| Sulphited then inoculated | Sulphur dioxide suppresses the resident population, then a cultured strain is added | Predictable timing, predictable aroma, reliable completion | Loses the succession entirely; a narrower aromatic range |
| Inoculated without sulphite | A cultured strain is added in sufficient quantity to dominate | Most of the reliability, with some early wild activity retained | The wild population can still assert itself if the inoculation is weak |
What "better" would have to mean
If better means more complex, spontaneous fermentation usually wins. The measured range of volatile compounds in a spontaneous cider is wider, and blind panels can generally distinguish the two.
If better means more reliable, inoculation wins by a large margin, and this is why it exists. A producer who cannot afford to lose a tank does not gamble one on the resident population.
If better means more expressive of the fruit, the answer is genuinely unresolved. A cultured strain produces a narrower, cleaner aromatic profile which can let fruit character through more clearly; a wild ferment adds character of its own that may either complement the fruit or bury it. Whether the added character is the place speaking or simply the building speaking is one of the open questions in cider science, and this site does not claim it is settled.
Where it is the tradition
Asturian and Basque sidra natural is spontaneously fermented in large chestnut or stainless vessels in cool llagares and sagardotegiak, without added sulphite in much traditional practice, and the resulting cider carries lactic and volatile characters that are part of the category rather than deviations from it.
Norman practice ferments spontaneously too, but under keeving, which restricts nutrients so severely that the ferment is slow and gentle from the outset. West Country farmhouse practice ferments spontaneously in wooden casks through a cold winter, which limits the speed and the temperature.
In all three cases the tradition combines spontaneous fermentation with something that constrains it — a cool building, a nutrient-poor juice, a slow winter. Spontaneous fermentation in a warm room with nutrient-rich juice is a different and much less forgiving proposition.
Also answered on this page
Questions this page covers, so you can tell at a glance whether it is the one you want.
- What is spontaneous fermentation?
- Do you have to add yeast to cider?
- Is wild yeast risky?
- What is a pied de cuve?
- Does wild fermentation taste of the orchard?
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.
- How does cider ferment — Yeast consumes the sugar in apple juice and produces roughly equal masses of ethanol and carbon dioxide, along with the esters and higher alcohols that give cider much of its aroma. In a wild ferment several yeast species take turns before *Saccharomyces* finishes the job.
- What is still unknown about cider — A great deal, and rather more than the confident tone of most cider writing suggests. Four gaps are large enough to affect what can honestly be said on almost any page of this site.
- 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.
- What is keeving and why does it make cider sweet
- Why has my cider stopped fermenting
- What are apiculate yeasts and do they die out — Apiculate yeasts such as Hanseniaspora dominate the first days of a spontaneous ferment and are usually described as dying out under rising alcohol. In cold Asturian ferments on low-sugar musts one of them was found at the end of every fermentation studied, so the usual account is a tendency rather than a rule.
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.
Peer-reviewed literature on cider fermentation microbiology
Various journals · peer-reviewed literature · registered as competent for this subject
Covers the microbial succession of spontaneous cider fermentation, the role of non-Saccharomyces yeasts in the early stages, malolactic conversion by Oenococcus and Lactobacillus species, and the organisms behind the principal spoilage faults.
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.
Institut Français des Productions Cidricoles (IFPC)
IFPC · research institute · retrieved 2026-08-24
The French technical institute for cider production. The authority for the French cultivar classification families, for keeving as an industrial process, and for the pectin and nitrogen chemistry that keeving depends on.
Servicio Regional de Investigación y Desarrollo Agroalimentario (SERIDA)
Principado de Asturias · research institute · retrieved 2026-08-24
The Asturian regional agri-food research service, and the technical authority behind the Asturian cultivar classification and the analysis of sidra natural. SERIDA’s own site has not been opened; what CiderHQ has read is SERIDA’s varietal characterisation as republished by the Consejo Regulador of DOP Sidra de Asturias, which credits it explicitly. The Asturian measurements therefore cite the Consejo rather than SERIDA — citing the body that did the work, at a document CiderHQ has not seen, would be exactly the kind of borrowed authority this register exists to prevent.
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.
Where to go next
- Learn about cider — The rest of the introductory material, grouped by the question it answers.
- Glossary — Any word on this page you did not recognise, defined in one or two sentences.
- Comparisons — What separates cider from the drinks it is most often confused with.