Tool
What does my titration reading mean?
Turns a burette reading into an acidity figure — and gives it in all three conventions at once, because the same cider is reported as malic acid in Britain, as sulphuric acid in older French practice and as tartaric acid by anything that came from winemaking. The three differ by up to a third.
Titratable acidity
Degassed. Dissolved carbon dioxide is an acid and will be counted as fruit acid if it is still there.
Bench sodium hydroxide is normally 0.1 N. Kit solutions vary and the figure is on the bottle.
Titratable acidity
5.0 g/L
As sulphuric acid: 3.68 g/L
How this is worked out
- Titrant used: 7.50 ml of 0.10 N alkali
- Milliequivalents of acid: 7.50 × 0.10 = 0.750 meq
- As malic acid: 0.750 × 67.045 ÷ 10.0 ml = 5.03 g/L
- As sulphuric acid: 3.68 g/L — the older French and some current European convention
- As tartaric acid: 5.63 g/L — what wine equipment and wine software usually assume
What this assumes (4)
- The three figures describe the same cider. Which one to quote depends on who is reading it, and a number given without its convention is ambiguous by up to a third.
- Titratable acidity is not pH. This counts how much acid is present, which governs how sharp the cider tastes; pH measures how strongly it is dissociated, which governs microbial risk and whether sulphite works.
- The endpoint matters. Titrating to pH 8.2 is the wine convention and is what these figures assume; titrating to a phenolphthalein colour change by eye lands near it and not on it.
- Degas the sample first. Dissolved carbon dioxide is itself an acid and will be counted as fruit acid if it is still there.
Three numbers, one cider
Titration counts how much acid is present by neutralising it with a known alkali and measuring how much it took. The arithmetic is stoichiometry and is not in dispute. What is in dispute is the unit.
The same milliequivalents can be reported as grams per litre of malic acid, of sulphuric acid or of tartaric acid, depending on which equivalent weight the convention uses. Britain and most of the modern cider literature use malic, which is the acid actually dominant in apples. Older French practice and some current European reporting use sulphuric. Anything that arrived from winemaking — most titration kits, most software — assumes tartaric, which apples contain essentially none of. The three figures differ by up to a third and none of them is wrong.
So this reports all three rather than choosing, on the same principle as the two ABV formulas: where a convention genuinely disagrees, showing one figure hides the part that matters. A titratable acidity quoted without its convention is ambiguous.
What it does not tell you
Not the pH. Titratable acidity is a quantity and pH is a strength, and they can move independently — a malolactic fermentation lowers titratable acidity a little and raises pH considerably more, so a cider can taste barely softer and be substantially less protected. The distinction in full, and what the pH then decides about sulphite.
Related tools
Where this reading comes from
Guides that reach this calculator, and what the number decides once you have it.