Organism
Kloeckera apiculata
The anamorph name for Hanseniaspora uvarum, still in wide use in cider writing, and often used loosely as a collective term for all apiculate yeasts.
Also called apiculate yeast, Hanseniaspora uvarum (anamorph).
- Kind
- Yeast
- Binomial
- Kloeckera apiculata
- Role
- Primary fermentation
What it does
- Names the asexual form of Hanseniaspora uvarum: the same organism, described from cultures in which no ascospores were seen, and therefore given a separate name under the dual nomenclature that fungal taxonomy used to permit.
- Serves in practice as shorthand in cider literature for the whole apiculate group — pointed, bipolar-budding yeasts dominating the first days of a ferment — regardless of which Hanseniaspora species is actually present.
- Carries the behaviour described under Hanseniaspora: rapid early growth, abundant acetate ester production, weak fermentation and death as ethanol rises past roughly 4% ABV.
Conditions it works in
What the organism tolerates and what suppresses it. These are the levers a maker actually has: temperature, acidity, air, alcohol and sulphite.
| Condition | What is recorded |
|---|---|
| Temperature | As for *Hanseniaspora uvarum*: roughly 10–30 °C. |
| pH | Roughly pH 3.0–4.0, the normal apple juice range. |
| Oxygen | Favoured by the oxygen present in fresh juice; declines as the ferment goes anaerobic. |
| Alcohol tolerance | Low, in the region of 4–6% ABV. |
| Sulphite tolerance | Sensitive; readily suppressed by juice sulphiting. |
What it produces
Compounds this organism makes. Which organism made a compound usually decides whether it reads as a feature or as a symptom.
Ethyl acetate
The most abundant ester in cider, giving lift and pear-drop at low concentration and nail varnish at high, and the earliest audible warning that acetic bacteria are at work.
Isoamyl acetate
The banana and pear-drop ester, made by yeast from isoamyl alcohol, and one of the clearest chemical signatures of a warm fermentation.
Acetaldehyde
The compound sitting one step short of ethanol, which smells of bruised apple and sherry, binds most of the sulphite added to a cider, and is the chemical signature of oxidation.
Acetic acid
The vinegar acid, made by bacteria oxidising ethanol whenever air reaches a cider, and the one fault in cider that no later processing can undo.
Ethanol
The alcohol yeast makes from fruit sugar, which converts a perishable juice into a keepable drink and carries most of its aroma to the nose.
Faults it causes
Faults this organism is implicated in. Several are faults only against a particular expectation — the same activity is a signature elsewhere.
Ethyl acetate taint
A solvent, nail-varnish or pear-drop aroma from ethyl acetate, the most abundant ester in cider and the one that turns from lift to fault over a narrow range.
Volatile acidity
The measurable fraction of acidity that can be steam-distilled off, dominated by acetic acid and read as vinegar sharpness in the nose and a hard, hot finish.
Where in the process it appears
Wild fermentation
Letting the microflora already present on the fruit and in the press house carry the ferment, in a succession rather than as a single organism.
Microbial succession
The ordered handover of a spontaneous ferment from apiculate yeasts to *Saccharomyces* to lactic acid bacteria, and the spoilage organisms waiting at the end of it.
Sulphiting
Adding sulphur dioxide to juice to suppress spoilage organisms and oxidative browning, at a level that only means anything once the juice pH is known.
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.
Maceration
Holding milled pomace before pressing so that phenolics, aroma precursors and pectin have time to move out of the solid tissue and into the juice.
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.
Pomace conditioning
Letting milled pomace stand before it goes to the press so that it drains better, presses faster and gives more juice.
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.
About Kloeckera apiculata
This record exists to resolve a name, not to describe a separate organism. Fungal taxonomy long permitted two names for one fungus: a teleomorph name for the sexual, spore-forming state and an anamorph name for the asexual state. Kloeckera apiculata was the anamorph name given to the asexual form of what is now called Hanseniaspora uvarum. They are one species. The corresponding anamorph of Hanseniaspora valbyensis, the apiculate reported most often from cider, is Kloeckera javanica.
Dual naming was abolished for fungi with the adoption of a one-fungus-one-name principle, and Hanseniaspora is the accepted genus. But a great deal of cider literature — including much of the classic English technical writing — was published before that, and uses Kloeckera consistently. A reader meeting the two names in two books should not conclude they describe two different organisms.
The looser usage is worth knowing too. In practical cider writing “Kloeckera” is frequently used as a category rather than a species: it means the apiculate yeasts, the lemon-shaped things visible in the first days under the microscope, without any claim about which species they are. That usage is understandable, and CiderHQ notes it rather than correcting it, but a statement about behaviour should attach to a species where the evidence supports one.
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.
- Can you fix a cider that has gone vinegary — Not really. Volatile acidity cannot be removed at small scale, and blending it away only dilutes it. The realistic options are to accept it, to blend a lightly affected batch into a much larger sound one, or to let it finish becoming vinegar.
- Why does my cider smell like nail varnish — That is ethyl acetate, formed when acetic acid combines with ethanol. In small amounts it reads as pear drops; above threshold it smells of solvent or nail varnish remover and usually accompanies rising volatile acidity.
- Why is sulphite added to cider — Sulphur dioxide suppresses spoilage bacteria and wild yeast before fermentation and protects the finished cider from oxidation. How much of it is active depends strongly on pH, which is why low-acid juice is harder to protect.
- How many calories are in cider — Roughly 40 to 60 kcal per 100 ml for most ciders, so a UK pint falls somewhere around 200 to 250 kcal. Alcohol contributes about 7 kcal per gram and residual sugar about 4, so both strength and sweetness matter.
- How much acetic acid is normal in cider — A small amount is present in every cider and contributes lift. Sound Asturian sidra natural has been measured at 0.2 to 0.3 g/L, and a clean modern cider much above about 0.7 g/L is generally showing a fault rather than a style.
Where to go next
- All organisms — Grouped by what each does in the ferment, and by what kind of organism it is.
- Compounds — The chemistry this microbiology produces.
- Troubleshooting — Work from the symptom in the glass back to the organism.
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.
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.