Glossary · Faults
Cider sickness
Also written sickness, la maladie, framboisé sickness. Each is a name for the same thing, which is why none of them has an entry of its own.
Definition
The historic name for a spoilage disorder of low-acid cider in which the drink turns turbid, loses colour, throws a deposit, produces gas and develops a milky, sometimes raspberry-like character.
- Subject
- Faults
- Also written
- sickness, la maladie, framboisé sickness
In more detail
Nineteenth and early twentieth-century writers used "sickness" for what modern microbiology has separated into several distinct bacterial disorders — framboise, ropiness, acrolein bitterness and lactic spoilage among them. The old accounts describe the symptoms accurately; the single disease they imply does not exist.
What all of them share is a cause: high pH, low acid, residual sugar and an inadequate sulphite regime. That is why sharp fruit in a blend was traditionally described as protective long before anyone could explain the mechanism.
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
Framboise
A spoilage disorder in which lactic acid bacteria acting on phenolic compounds produce a strong raspberry-like aroma alongside a characteristic haze and loss of colour.
Faults
Ropiness
A texture fault in which the cider becomes viscous and pours in an oily rope, caused by lactic acid bacteria producing extracellular glucan polysaccharide.
Chemistry
Acrolein
A pungent compound formed when certain lactic acid bacteria metabolise glycerol. Reacting with phenolics, it produces an intense and persistent bitterness known historically as *amertume*.
Microbiology
Lactic acid bacteria
The bacteria that convert malic acid to lactic acid and, in other conditions, produce the disorders of ropiness, mousiness and acrolein bitterness. *Oenococcus*, *Lactiplantibacillus* and *Lactobacillus* species dominate in cider.
Chemistry
pH
A logarithmic measure of hydrogen ion activity, and in cider the single most important number for microbial safety. Apple juice usually falls between pH 3.2 and 3.9.
Fruit
Sharp
In the Long Ashton classification, a cider apple high in acid and low in tannin. Sharps supply freshness and lower the pH of a blend into a range where spoilage organisms are less comfortable.
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.
Long Ashton Research Station cider fruit analyses
National Fruit and Cider Institute / University of Bristol · research institute · registered as competent for this subject · covers 1903–2003
The foundational body of cider-fruit science in English. Long Ashton produced the acid-and-tannin classification that divides cider apples into sweet, sharp, bittersweet and bittersharp, and analysed hundreds of cultivars grown at its Somerset site. Its figures are historic measurements of specific fruit at a specific place, not universal constants — a distinction CiderHQ preserves in every measurement record that cites it.