Glossary · Sensory
Acidity
Also written sharpness. Each is a name for the same thing, which is why none of them has an entry of its own.
Definition
The perception of sourness, and the sensation of freshness and mouth-watering it brings. It correlates with both titratable acidity and pH, but neither predicts it exactly.
- Subject
- Sensory
- Also written
- sharpness
In more detail
Perceived acidity depends on what accompanies it: sugar suppresses it, tannin can accentuate it, carbonation sharpens it, and temperature changes it. Malolactic conversion lowers it more than the acid figures alone suggest, because lactic acid tastes softer than malic at the same concentration.
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.
Chemistry
Titratable acidity
The total concentration of titratable acid in a juice or cider, measured by neutralising a sample with alkali to an end point and expressed as an equivalent of malic acid in grams per litre.
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.
Chemistry
Malic acid
The dominant acid of apples and pears, giving the sharp, clean acidity of fresh juice. Its name comes from *malum*, the Latin for apple.
Sensory
Balance
The relationship between a cider’s sweetness, acidity, tannin, alcohol and carbonation, judged by whether any one of them dominates unintentionally.
Sensory
Sweetness
The perception of sugar, and in perry of sorbitol. It is suppressed by acid, tannin and carbonation, so measured sugar and perceived sweetness diverge routinely.
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.
Washington State University cider research programme
Washington State University Northwestern Washington Research and Extension Center · university · passage verified 2026-08-24
The single most useful open cider dataset CiderHQ has found. The programme’s cultivar performance database gives juice chemistry, orchard behaviour, bloom and harvest timing and cider-maker tasting notes for 73 cultivars grown at one maritime site over fifteen years, and — unusually — publishes its classification thresholds alongside its figures, so the classification can be checked rather than taken on trust. It also states outright that its results diverge from the English ones. Read in full on 2026-08-24 and transcribed into `data/trials/wsu-mount-vernon.ts`; four published figures were found to be impossible and are withheld there with their reasons.
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.