Glossary · Faults
Light strike
Also written lightstruck, sunstruck. Each is a name for the same thing, which is why none of them has an entry of its own.
Definition
Damage caused by light, particularly in the ultraviolet and near-blue range, generating sulphur compounds that give a cabbage or skunky aroma in ciders bottled in clear or green glass.
- Subject
- Faults
- Also written
- lightstruck, sunstruck
In more detail
Riboflavin acts as the photosensitiser, so the reaction proceeds in ordinary retail lighting as well as in sunlight, and it can occur within hours in clear glass. Brown glass gives substantial protection, cans and bag-in-box complete protection, and clear bottles none.
Where this is covered properly
The glossary defines; these pages explain. Each is described in its own words.
Related terms
Terms that belong to the same part of the subject, or that this one is routinely confused with.
Faults
Reduction
The accumulation of volatile sulphur compounds — hydrogen sulphide, mercaptans and disulphides — in an oxygen-starved ferment or maturing cider, giving rotten egg, drain and rubber aromas.
Faults
Mercaptan
A sulphur compound formed when hydrogen sulphide reacts with ethanol and other constituents, smelling of onion, rubber, garlic or drains. Far harder to remove than the hydrogen sulphide it comes from.
Serving
Cellar conditions
How cider is kept before opening: cool, dark and stable. Warmth accelerates ageing and oxidation, light causes light strike in clear glass, and temperature swings can precipitate haze.
Equipment
Crown cap
The pressed metal closure crimped over a bottle lip, lined with a compressible seal. It holds pressure reliably and is the standard closure for bottle-conditioned cider.
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.
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.