Sensory descriptor
Apple pomace
The wet, sweet-sour smell of freshly milled and pressed pomace: cut-apple aldehydes over the first traces of wild fermentation and browning.
Also called Milled fruit, Pomace heap.
- Aroma family
- Fresh apple
- Does it indicate a fault?
- No — a normal part of cider and perry aroma
What causes it
Pomace is the whole fruit with the juice removed, and its smell is a three-part mixture. The cut-tissue aldehydes are at maximum, because every cell has been broken. Polyphenol oxidase is working on chlorogenic acid in air, adding the faintly sweetish, browning note that goes with enzymatic oxidation. And the wild yeast population on the fruit skin — chiefly Hanseniaspora and Metschnikowia species — has begun to work on exposed sugar, generating ethyl acetate and other acetate esters within hours. The proportions shift fast: a heap smells of apple in the first hour and of ferment by the next morning.
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.
Hexanal
The green-apple aldehyde generated within seconds of breaking fruit tissue, which gives fresh juice its cut-grass smell and is largely converted away by the yeast.
Polyphenol oxidase
The copper enzyme that turns cut apple brown within seconds, and the reason a cidermaker has to decide, at the press, whether to let the juice oxidise or to stop it.
Chlorogenic acid
The most abundant single phenolic in apple juice, the preferred substrate of the enzyme that browns it, and the precursor of one of the volatile phenols behind farmyard character.
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.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
Milling
Reducing whole fruit to a pulp so that the press has cell walls it can drain, rather than intact apples it can only bruise.
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.
Pomace conditioning
Letting milled pomace stand before it goes to the press so that it drains better, presses faster and gives more juice.
Pomace handling
What is done with the pressed cake once the juice is off it — feed, pectin extraction, composting, digestion or orchard spreading — and why a wet acidic heap beside the press is a problem.
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 Apple pomace
This is a production-side descriptor rather than a glass-side one, and it is included because it is the reference standard cidermakers actually calibrate against. Where a finished cider shows it, the cause is usually extended maceration, pressing from a heap that stood too long, or a wild ferment that carried the pomace’s own microflora through into the vat.
In a finished drink it sits close to two other descriptors and should be distinguished from both: from apple skin, which is dry and waxy without the fermenting edge, and from cider shop, which is the ferment note without the fresh-fruit layer underneath.
Others in the fresh apple family
Crisp, green, just-cut apple and apple skin.
Fresh-cut apple
The smell of a cut apple surface, produced within seconds of the fruit tissue being broken by six-carbon aldehydes released from membrane fats.
Green apple
A harder, sharper apple note than fresh-cut apple, driven by (E)-2-hexenal and reinforced by high malic acid.
Apple skin
The dry, faintly waxy and slightly bitter aroma of the fruit’s surface rather than its flesh, carried by cuticular waxes, hexyl esters and skin-concentrated phenolics.
Pressed apple juice
The full, sweet, unfermented smell of fresh juice, met in cider where residual sugar and surviving fruit esters combine.
Crab apple
A small-fruit character combining very high acidity, hard green aldehydes and a marked phenolic grip.
Russet apple
A dry, nutty, faintly pear-like apple character associated with russeted skin and high soluble solids.
Unripe apple
A hard, starchy, low-aroma character from fruit milled before the climacteric, with acid high and esters not yet formed.
Apple core
A faintly bitter, faintly almond-like note from crushed pips and core tissue passing through the mill with the flesh.
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 are apples milled for cider
- 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.
- What do you do with apple pomace — Most pomace goes to livestock feed, composting or anaerobic digestion; some is dried for pectin extraction. Fresh heaps ferment and attract vinegar flies, so it is a hygiene problem as much as a by-product.
- What is maceration in cider making — Maceration is letting milled pomace stand before pressing, so that enzymes soften the tissue and phenolics and aroma move from the skins into the juice. It raises both colour and tannin, and raises the risk of oxidation with them.
- What is a traditional west country cider blend — Predominantly bittersweet fruit for body and tannin, with a proportion of sharp fruit for acidity and sometimes a smaller share of bittersharps for both. The exact composition varied by farm and by what was in the orchard.
- What is wild fermented cider
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.
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.
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.