Sensory descriptor
Fusel
A hot, heavy, spirituous impression from elevated higher alcohols, felt as warmth as much as smelled.
Also called Hot alcohol, Fusel oil.
- Aroma family
- Fermentation-derived
- Does it indicate a fault?
- It depends on the style it is met in
What causes it
Higher alcohols — isoamyl alcohol, isobutanol, active amyl alcohol, 2-phenylethanol and propanol — are produced by yeast through the Ehrlich pathway, in which amino acids are deaminated, decarboxylated and reduced. Production rises sharply when assimilable nitrogen is short, because yeast must scavenge nitrogen from amino acids, and again when fermentation temperature is high. Apple juice is naturally low in assimilable nitrogen compared with grape must — often well under 100 mg/L — so cider is more prone to this than wine, and it is one of the principal arguments for nitrogen management.
Higher alcohols at moderate levels give body and warmth and are part of what makes a cider taste like a fermented drink rather than juice with alcohol in it. Elevated, they read as hot and harsh and can make a 6% cider seem stronger than a well-balanced 8% one.
The compounds responsible
Where the molecule is established. Some descriptors in this lexicon name a compound the compound register does not yet hold a record for; those are named in the cause above instead.
Higher alcohols
The group of larger alcohols yeast makes from amino acids, welcome as background complexity in trace and harsh and solvent-like in quantity.
Isoamyl alcohol
The most abundant fusel alcohol in cider, made from leucine, and the direct precursor of the banana ester that defines warm-fermented styles.
2-Phenylethanol
The yeast-made alcohol responsible for the rose and honey note in cider, produced from phenylalanine and one of the few floral aromas that is not carried in from the fruit.
Yeast-assimilable nitrogen
The nitrogen a yeast can actually use, which apple juice is chronically short of — the shortage behind both stuck fermentations and rotten-egg aromas, and the shortage keeving deliberately makes worse.
Amino acids
The largest usable nitrogen fraction in apple juice, and the raw material from which yeast builds both its own protein and most of the aroma compounds a cider carries.
The organisms that make it
Where a specific organism is implicated rather than the fruit. Naming one answers a different question from naming a molecule: what is in the cellar, rather than what is in the glass.
Saccharomyces cerevisiae
The yeast that finishes essentially every cider, whether it arrives in a sachet or from the fruit, the press and the vessel.
Saccharomyces bayanus
A name applied both to a hybrid *Saccharomyces* lineage and, loosely, to a whole class of commercial high-alcohol yeasts, and one of the least stable names in fermentation microbiology.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
Yeast nutrition
What a fermenting yeast population actually needs from apple juice — assimilable nitrogen, vitamins and membrane lipids — and what goes wrong when the juice cannot supply it.
Nutrient addition
Supplementing a characteristically nitrogen-poor juice so that yeast can complete fermentation without producing sulphide or stalling.
Fermentation temperature control
Managing the temperature at which a ferment runs, which sets not only how fast it goes but which aromatics survive it and what the finished cider tastes of.
Inoculated fermentation
Starting a ferment by pitching a chosen yeast culture so that one known strain, rather than the fruit’s resident population, does the work.
The fault it points at
Meeting this descriptor above a certain intensity is how the fault below is usually noticed first.
Fault
The set of characters a nitrogen-starved fermentation produces together — sulphide, a stalled or dragging ferment, harsh higher alcohols and a thin, hard cider.
Where it is usually met
Fruit and styles this character is recorded in. A record here is where the descriptor is commonly found, not a claim that every example shows it.
About Fusel
Fusel character is the most direct sensory report on nitrogen status in a cider fermentation, and cider’s low natural YAN makes it a recurring problem rather than an occasional one. Cornell and other programmes have published extensively on the relationship.
It is also the descriptor most often mistaken for alcohol level. A drinker calling a cider hot is usually perceiving higher alcohols, not ethanol, and the two are independent.
Others in the fermentation-derived family
Solvent, nail varnish, bread, yeast, cider-shop.
Nail varnish
The sharp solvent lift of ethyl acetate above threshold, the commonest volatile fault-adjacent note in cider.
Bread dough
A raw, yeasty, faintly sour note from live yeast in suspension, characteristic of unfiltered and bottle-conditioned cider.
Solvent
A general chemical, thinner-like impression from ethyl acetate and higher alcohols together.
Cider shop
The characteristic smell of a working cider house — ferment, wood, fruit and a trace of acetic lift together.
Fresh yeast
The clean, faintly sulphidic smell of an active yeast population, met in young cider and during fermentation.
Lees
A cloudy, faintly bitter, sedimentary character from yeast and fruit solids carried into the glass.
Yeast extract
A savoury, umami, meaty-broth note from yeast autolysis during extended lees contact.
Fermenting vat
The pungent, CO2-lifted smell of a ferment in full activity, met in very young cider straight from the vessel.
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 temperature should cider ferment at — Most cider is fermented cool, commonly between about 12 and 18 °C. Cooler ferments keep more fruit aroma and run slower; above the low twenties the cider tends towards hot, solvent-like higher alcohols.
- 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 make cider from shop bought apple juice — Yes, provided the juice contains no preservative — check for potassium sorbate or benzoate on the label. Pasteurised juice ferments perfectly well once yeast is added, because pasteurisation removes the organisms but not the sugar.
- What is scrumpy — Scrumpy is an informal West Country word for strong, still, usually cloudy farmhouse cider. It has no legal definition, so it describes a style expectation rather than a guaranteed method.
- What is yan and why does cider juice run short of it — Yeast assimilable nitrogen is the nitrogen yeast can actually use. Apple juice is usually short of it — in one Virginia survey of 108 samples, 94 per cent fell below the level wine practice treats as a minimum — which is why cider ferments stall more readily than wine ferments.
- What is yeast nutrition in cider making
Where to go next
- The sensory model — The thirteen structural dimensions and the twenty aroma families, in full.
- Compounds — The chemistry behind the words.
- Troubleshooting — When a perception turns out to be a problem, this is where it is diagnosed.
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.
Cornell Cider Research and Extension programme
Cornell University, School of Integrative Plant Science · university · passage verified 2026-08-24
Runs cultivar trials in New York State and publishes juice chemistry for European cider varieties grown in a North American climate — the single most useful counterweight to treating English figures as universal.
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.
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.