Sensory descriptor
Metallic
A blood-and-tin taste from dissolved iron or copper, which also catalyses oxidation.
Also called Tinny, Inky.
- Aroma family
- Volatile and fault-related
- Does it indicate a fault?
- Usually, yes
What causes it
Iron and copper enter cider from unsuitable equipment — mild steel, brass fittings, worn tinned surfaces — and from copper-based orchard sprays. Both are perceptible as a metallic taste at low milligram-per-litre levels, and both are far more consequential as catalysts than as flavours: they accelerate the oxidative reactions that produce acetaldehyde and (E)-2-nonenal, and iron in particular participates in the formation of hazes with tannin and phosphate. A metallic-tasting cider therefore usually has an oxidation problem developing behind the taste.
No level is acceptable, and the catalytic effects begin below the taste threshold, so a cider with a metal pickup problem is being damaged before anyone can taste it.
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.
Dissolved oxygen
Essential to a healthy yeast population at the start of fermentation and the principal enemy of a cider from the moment fermentation ends.
Ascorbic acid
An oxygen scavenger that protects colour and aroma while it lasts and can promote browning once it is exhausted, which is why it is never used without sulphur dioxide.
Total phenolics
The single number used to summarise everything phenolic in a juice, useful for comparing fruit and misleading whenever it is used to predict how a cider will taste.
What raises it
Processes that increase this character, or preserve it where it would otherwise be lost.
Fining
Adding a reactive agent that binds a target colloid and carries it to the bottom, chosen according to whether the problem is tannin, protein or a phenolic taste fault.
Sanitation
The cleaning and sanitising discipline that underlies every other process, and why removing soil must come before any attempt to kill organisms.
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.
Fermentation vessels
The container a cider ferments in — wood, stainless, plastic, glass or concrete — and how its permeability, thermal mass and resident microflora shape the result.
Canning
Filling cider into lined aluminium, a format that blocks light completely, seals tightly and depends entirely on an intact polymer coating between an acidic drink and the metal.
The fault it points at
Meeting this descriptor above a certain intensity is how the fault below is usually noticed first.
Fault
A metallic, inky or blood-like taste from dissolved iron, copper or zinc picked up from equipment, usually accompanied by accelerated oxidation.
About Metallic
Metallic taint is worth recording carefully because it is a leading indicator rather than a terminal one. Its main significance is what it predicts about the cider’s oxidative stability.
The remedy is to find the metal: modern practice is to eliminate reactive metals from every contact surface, and where a pickup has already occurred, fining agents can remove some of it.
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.
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.
Acetone
A harsher, more chemical solvent note than ethyl acetate alone, from ketones alongside high volatile esters.
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.
- Is cider vegan — Cider itself is a plant product, but some producers clarify it with animal-derived finings such as gelatine, isinglass or chitosan. Vegan status therefore depends on the fining regime, which is why some ciders are certified and others are not.
- 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.
- What should i ferment cider in — Anything inert, cleanable and closable: glass demijohns, food-grade plastic, stainless steel, or a wooden cask if you can keep it sound. Vessel shape and material change how much oxygen the cider sees and how fast it clears.
- Does cider contain antioxidants — Cider carries apple polyphenols, and tannic bittersweet ciders carry considerably more than pale ones made from dessert fruit. What that means for health is a clinical question this site does not adjudicate.
- How is cider canned
- Is vitamin c useful in cider making — It is an antioxidant and is sometimes added at pressing, but it is not a substitute for sulphite: it protects against oxidation and does nothing antimicrobial, and once exhausted it can accelerate browning rather than prevent it.
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.
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.