Glossary · Equipment
pH meter
Definition
An electrode instrument measuring hydrogen ion activity directly. It is the only practical way to determine a juice’s pH accurately, since indicator papers lack the resolution the decisions require.
- Subject
- Equipment
In more detail
Meters need calibration against buffer solutions before each session and a clean, hydrated electrode. Given that sulphite efficacy and spoilage risk both turn on tenths of a pH unit, an uncalibrated meter is worse than none.
Related terms
Terms that belong to the same part of the subject, or that this one is routinely confused with.
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.
Fermentation
Sulphiting
Adding sulphur dioxide, usually as potassium or sodium metabisulphite, to juice or cider to suppress spoilage organisms, inhibit oxidation and enzymatic browning, and give a selected yeast a clear field.
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
Molecular sulphur dioxide
The undissociated fraction of free sulphur dioxide, and the only form that is antimicrobial. Its share of the free sulphite is governed by pH and falls sharply as pH rises.
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.
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.