Sensory descriptor
Garlic
A pungent allium note from specific thiols and disulphides, occasionally from orchard spray residues.
Also called Onion, Allium.
- Aroma family
- Sulphur
- Does it indicate a fault?
- Usually, yes
What causes it
Garlic and onion notes in cider come from a small group of sulphur compounds distinct from the parent hydrogen sulphide: allyl and methyl sulphides and disulphides, and certain thiols formed by reaction of sulphide with fermentation intermediates. A second and less common route is residue: elemental sulphur applied in the orchard as a fungicide, if carried into the mill in quantity, is reduced by yeast during fermentation and produces a marked and characteristic allium note. Harvest interval after sulphur sprays is the relevant control.
No level is acceptable. Where it originates in spray residue rather than in nitrogen stress, adding nutrient will not prevent it and the intervention has to happen in the orchard.
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.
Mercaptans
What hydrogen sulphide becomes if it is left alone: onion, garlic and rubber notes that are far harder to remove than the gas they came from.
Hydrogen sulphide
The rotten-egg gas a nitrogen-starved yeast produces, detectable at concentrations too small to measure easily, and removable only if it is caught before it becomes something worse.
Dimethyl sulphide
A sulphur compound that reads as cooked vegetable in quantity and adds an indefinable savoury depth in trace, and which builds slowly during storage rather than during fermentation.
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.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
Pest and disease management
Keeping scab, canker, rots and the main insect pests to a level the orchard can carry, at a cosmetic standard well below dessert fruit but without allowing rot into the crop.
Fruit washing
Removing soil, grass, stones and surface contamination from gathered fruit, usually in a water flume, before it reaches the mill.
Racking
Moving cider off the sediment it has thrown, which both cleans the liquid and — by taking yeast and nitrogen away with the deposit — slows what is left of the ferment.
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.
The fault it points at
Meeting this descriptor above a certain intensity is how the fault below is usually noticed first.
Fault
Onion, garlic, burnt rubber and cooked-cabbage aromas from thiols and disulphides formed when hydrogen sulphide is left in cider long enough to react onwards.
About Garlic
This descriptor earns its place because it points at a cause outside the cellar. A producer meeting persistent allium character in fruit from a particular block should look at the spray record before adjusting the fermentation.
It is one of the sulphur notes least amenable to correction once formed, and it belongs with the mercaptan group rather than with simple reduction.
Others in the sulphur family
Rotten egg, struck match, drains, rubber, cooked cabbage.
Rotten egg
Hydrogen sulphide from yeast under nitrogen stress — the commonest sulphur fault and the most correctable.
Drains
A heavy, stagnant, sewer-like note from mercaptans formed when hydrogen sulphide is left to react.
Struck match
The sharp, mineral, matchhead note of free sulphur dioxide above its perception threshold.
Cooked cabbage
A vegetal sulphur note from dimethyl sulphide, rising slowly during storage rather than during fermentation.
Flinty
A sub-threshold reductive note read as struck flint rather than as sulphur, the mildest state of reduction.
Lightstruck
A skunky, sulphidic note produced when light degrades riboflavin in clear or green glass.
Rubber
A burnt-rubber note from disulphides and higher mercaptans, generally a late stage of reductive fault.
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.
- 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.
- What is racking in cider making — Racking is siphoning cider off the sediment it has thrown into a clean vessel, leaving the lees behind. It clarifies the cider and, in traditional practice, is also used to slow a ferment by removing yeast with the lees.
- What is yeast nutrition in cider making
- Are apples washed before making 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.
NIAB (incorporating East Malling Research)
NIAB · research institute · retrieved 2026-08-24
East Malling developed the M-series apple rootstocks that determine tree size in essentially every modern orchard, cider orchards included. The authority CiderHQ uses for rootstock behaviour.
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.
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.