Glossary · Chemistry
Ethyl acetate
Definition
The ester of ethanol and acetic acid. At low concentration it reads as fruity and solvent-like; at higher concentration it is the nail-varnish note that accompanies acetic spoilage.
- Subject
- Chemistry
In more detail
Ethyl acetate is produced both by acetic acid bacteria and by certain apiculate yeasts early in fermentation, which is why a small amount is normal in wild-fermented cider. It is perceptible at lower concentrations than acetic acid itself, so it is usually the first warning that a cask is going over.
Where this is covered properly
The glossary defines; these pages explain. Each is described in its own words.
Chemistry
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.
Fault
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.
Related terms
Terms that belong to the same part of the subject, or that this one is routinely confused with.
Chemistry
Volatile acidity
The fraction of a cider’s acidity that can be distilled off — overwhelmingly acetic acid — measured separately from fixed acidity and used as an index of bacterial spoilage.
Chemistry
Acetic acid
The acid of vinegar, produced in cider by acetic acid bacteria oxidising ethanol and, in small amounts, by yeast during fermentation. It is the main constituent of volatile acidity.
Faults
Acetification
The oxidation of ethanol to acetic acid by acetic acid bacteria, turning cider progressively into vinegar. It requires oxygen and is the classic fault of a slack, part-empty cask.
Microbiology
Apiculate yeast
Lemon-shaped, weakly fermenting yeasts — *Hanseniaspora* and its anamorph *Kloeckera* — that dominate the first days of a wild cider fermentation before alcohol suppresses them.
Chemistry
Esters
Compounds formed between an alcohol and an acid, produced in quantity by yeast during fermentation, and responsible for much of a cider’s fruity aroma.
Where to go next
- Cider glossary — The whole vocabulary, by subject and A–Z.
- Comparisons — Terms that are only really clear when set against the thing they are not.
- Search — Finds terms by their aliases and by their spellings in other languages.
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.
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.