Equipment
Titration kits for total acidity
How do I measure the acidity of cider?
In short
A known volume of degassed cider or juice is placed in a flask and a standard sodium hydroxide solution is added from a burette or syringe until the acid is exactly neutralised. The volume of alkali used is proportional to the acid present.
In cider the result is conventionally expressed as grams per litre of malic acid, because malic is the dominant acid in apples. Wine convention uses tartaric acid instead, so a figure quoted without saying which acid it is expressed as is ambiguous and can differ by a noticeable factor.
This is the number that predicts how sharp a cider tastes, and the number a blender works with. It is distinct from pH and neither substitutes for the other.
How the measurement works
Titration exploits a simple stoichiometry: alkali neutralises acid mole for mole of available hydrogen ion. If the concentration of the alkali is known exactly, then the volume needed to reach neutralisation gives the amount of acid in the sample directly. The arithmetic that converts that volume into grams per litre of malic acid depends on the alkali concentration, the sample volume and the equivalent weight of the acid it is being expressed as.
The endpoint in wine and cider work is conventionally taken at pH 8.2 rather than at pH 7, because the weak organic acids involved are not fully neutralised at 7. That convention is what makes results comparable between laboratories, and it is why a titration followed with a pH meter is set to stop at 8.2.
The sample must be degassed first. Dissolved carbon dioxide is itself an acid and will be titrated along with everything else, inflating the result. Degassing is done by warming, by vigorous stirring, or under vacuum, depending on the kit.
The endpoint problem
Simple kits use phenolphthalein, an indicator that turns from colourless to pink around the right pH. In white wine or pale juice this works well. In a deeply coloured traditional cider — brown, orange or amber from oxidised phenolics — the colour change is masked and the endpoint is a matter of guesswork, which is the commonest reason a home titration disagrees with a laboratory.
There are two practical answers. The first is to dilute the sample heavily with distilled water before titrating: dilution does not change the amount of acid present, so it does not change the result, but it makes the colour change visible. The second, and better, is to titrate to a pH meter reading of 8.2 and ignore the indicator entirely, which removes the judgement from the process.
Kits sold for home use vary considerably in quality. What determines accuracy is the accuracy of the sample measurement, the accuracy of the alkali concentration, and the resolution of whatever delivers the alkali. A syringe graduated in half millilitres is a coarser instrument than a burette, and on a small sample that coarseness dominates the result.
Reagents and their limits
Sodium hydroxide solution absorbs carbon dioxide from the air and weakens over time, so its concentration drifts. Kits supply it in sealed containers with a shelf life for that reason, and a bottle that has been open on a shelf for two seasons will give results that read low. Where the number matters, the alkali is standardised against a known acid before use, or replaced.
Sodium hydroxide is caustic, and even the dilute solutions used in titration kits will damage eyes. Eye protection is worn, the supplier’s safety data sheet governs handling and disposal, and it is stored where it cannot be mistaken for anything else.
The instruments — pipette, flask, burette — are rinsed with distilled water and then with a little of the solution they will hold, so that residual water does not dilute what is being measured.
What the number is used for
- Blending. Acidity is one of the two or three properties a blender works with directly, and a bench blend is calculated from measured acidities rather than guessed.
- Judging whether a juice needs acid adjustment before fermentation, which for low-acid bittersweet fruit is a real question with microbiological as well as sensory consequences.
- Tracking malolactic conversion, which lowers total acidity as the sharper malic acid is converted to the softer lactic acid. A falling titratable acidity with no other explanation is the usual first sign it has happened.
- Explaining a cider that tastes flat despite a low pH, or sharp despite a high one — the two figures diverging is itself informative.
Also answered on this page
Questions this page covers, so you can tell at a glance whether it is the one you want.
- How do you test acidity in cider?
- What is titratable acidity?
- Why does my acid test not change colour?
Related
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.
- Do i need a ph meter for cider, and how do i keep it accurate — A pH meter consists of a glass electrode that develops a small voltage proportional to hydrogen ion activity, a reference electrode, and a meter that converts that voltage into a pH reading.
- What is malic acid and why does it matter in cider — Malic acid is the acid of apples and supplies almost all the sharpness a cider has. It also sets pH, which decides how well sulphite works and how exposed the cider is to spoilage, so it does far more work than its taste suggests.
- How do i balance acid and tannin in a blend — Acid and tannin do different jobs and cannot substitute for each other: acid gives freshness and microbiological safety, tannin gives structure and length. A blend short of acid tastes flabby however tannic it is.
- What is malolactic fermentation — Malolactic fermentation is a bacterial conversion of sharp malic acid into softer lactic acid, releasing carbon dioxide. It lowers total acidity and raises pH, and in cider it is often the source of a farmyard or buttery note as well.
- Which measurements can i do myself and which need a laboratory
- Why does cider contain lactic acid — Because malolactic bacteria converted the malic acid into it. Malic acid has two acid groups and lactic acid has one, so roughly half the titratable acidity disappears and the cider tastes softer.
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.
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 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.
Where to go next
- Cider making equipment — The rest of the equipment material, grouped by what each piece is for.
- How cider is made — The methods this equipment exists to carry out.
- Troubleshooting — The faults that are traced back to equipment and to cleaning.