Glossary · Chemistry
Malic acid
Definition
The dominant acid of apples and pears, giving the sharp, clean acidity of fresh juice. Its name comes from malum, the Latin for apple.
- Subject
- Chemistry
In more detail
Malic acid is a dicarboxylic acid, which is why converting it to the monocarboxylic lactic acid in malolactic fermentation removes so much perceived acidity. Concentrations in cider apple juice range from a few grams per litre in bittersweets to well over ten in sharp cultivars.
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
Lactic acid
A softer, milder acid produced from malic acid by lactic acid bacteria, and in smaller quantities by yeast. Its arrival is what makes a malolactic cider taste rounder.
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.
Fermentation
Malolactic fermentation
The bacterial conversion of malic acid into lactic acid and carbon dioxide, which lowers total acidity, raises pH slightly and softens the drink. It is a bacterial process, not a yeast fermentation.
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.
Chemistry
Citric acid
A minor acid in apples but a significant one in pears, where it makes up a larger share of total acidity and behaves differently from malic acid under bacterial attack.
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.
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.