Sensory descriptor
Acetone
A harsher, more chemical solvent note than ethyl acetate alone, from ketones alongside high volatile esters.
Also called Ketone, Sharp solvent.
- Aroma family
- Volatile and fault-related
- Does it indicate a fault?
- Usually, yes
What causes it
Where ethyl acetate is high and the fermentation has also produced elevated levels of ketones and of ethyl acetate’s harsher relatives, the perception moves from nail varnish, which has a fruity edge, towards the flatter and more chemical smell of acetone itself. Contributing compounds include the diketones of the diacetyl family at high concentration and, in some spoilage situations, ketones from bacterial metabolism. It is a composite descriptor for the harshest end of the volatile fault range and generally arrives with high volatile acidity.
No level is acceptable. The descriptor is reserved for the point at which the solvent character has lost the fruit edge that pear drop and nail varnish retain.
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.
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.
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.
Diacetyl
The butter compound, made mainly by lactic acid bacteria and perceptible at very low concentration, which is a defining part of some traditional ciders and an obvious fault in others.
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.
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.
Clostridium species
Spore-forming anaerobic bacteria of soil and windfall fruit that cause butyric spoilage in low-acid products, and are essentially excluded from cider by its acidity.
Hanseniaspora valbyensis
The apiculate yeast most consistently reported as dominating the first days of a spontaneous cider fermentation, and a major contributor to its aroma.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
Topping up
Refilling a maturing vessel as evaporation and racking losses lower the level, so that no significant surface of cider is ever left in contact with air.
Sulphite stabilisation
Managing free sulphur dioxide through maturation and at packaging so that a useful antimicrobial and antioxidant fraction survives into the bottle.
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.
The fault it points at
Meeting this descriptor above a certain intensity is how the fault below is usually noticed first.
Fault
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.
About Acetone
Acetone is included because tasters distinguish it from nail varnish reliably and the distinction carries information: nail varnish suggests ethyl acetate alone, acetone suggests a broader spoilage picture.
A cider recorded as acetone should be assessed for volatile acidity and for the other bacterial faults at the same time, since it rarely occurs in isolation.
Others in the volatile and fault-related family
Vinegar, glue, mousiness, sourness out of place.
Vinegar
Acetic acid from acetic acid bacteria oxidising ethanol in the presence of air — the classic cider spoilage.
Glue
Ethyl acetate at fault concentration, past the solvent stage and into adhesive.
Mousy
A retronasal-only taint of mouse cage and stale grain, from tetrahydropyridines produced by lactic bacteria and Brettanomyces.
Flat and lifeless
The absence of aroma and lift where both were intended — a fault defined by what is missing rather than present.
Metallic
A blood-and-tin taste from dissolved iron or copper, which also catalyses oxidation.
Peppery bitterness
A harsh, burning bitterness from acrolein formed when lactic bacteria degrade glycerol.
Ropy
An oily, viscous, pouring-in-a-thread texture from bacterial exopolysaccharide, with little aroma of its own.
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.
- How do i sterilise cider bottles — Wash them clean first, then sanitise with a no-rinse sanitiser or a sulphite solution, and fill while still wet with it. Bottles that look clean but have dried deposits inside are the usual source of bottle spoilage.
- 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.
- Why does my cider smell of nail varnish or solvent — Almost always ethyl acetate, the ester of acetic acid and ethanol. It is made by stressed yeast and by acetic acid bacteria, and it is perceptible at a small fraction of the concentration the acid itself needs, so it usually announces a problem before the vinegar does.
- How much headspace should a cider fermenter have
- 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.
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.
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.
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.