Glossary · Chemistry
Residual sugar
Also written RS. Each is a name for the same thing, which is why none of them has an entry of its own.
Definition
The fermentable sugar remaining in a finished cider, usually expressed in grams per litre. It is what sweetness legislation and style bands are written against.
- Subject
- Chemistry
- Also written
- RS
In more detail
Residual sugar and perceived sweetness are related but not the same. Acid, tannin and carbonation all suppress the perception of sweetness, so the same 20 g/L reads differently in an austere bittersharp cider and in a soft, low-acid one. Sorbitol in perry adds sweetness without being fermentable sugar at all.
Related terms
Terms that belong to the same part of the subject, or that this one is routinely confused with.
Cider
Dry
A cider or perry with little or no residual sugar, in which fermentation has taken the sugars essentially to completion.
Cider
Medium
A cider between dry and sweet, carrying enough residual sugar to be noticeable without dominating. British retail practice uses it as the middle of a three-step scale.
Cider
Sweet cider
In Britain and Europe, a cider at the sweet end of the sweetness scale, with enough residual or added sugar to taste distinctly sweet. In North America, the same phrase means fresh unfermented apple juice, usually unfiltered.
Fermentation
Attenuation
The proportion of the original sugar that fermentation has consumed, calculated from the fall in gravity from the starting to the current reading and expressed as a percentage.
Fermentation
Back-sweetening
Adding sugar, juice or concentrate to a fully fermented cider to reach a target sweetness. Because the added sugar is fermentable, the cider must then be stabilised or kept cold.
Chemistry
Sorbitol
A sugar alcohol present in substantial quantity in pears and in smaller amounts in apples. Yeast does not ferment it, so it survives fermentation and leaves a fully dry perry tasting faintly sweet.
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 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.
European Cider and Fruit Wine Association (AICV)
AICV · specialist organisation · retrieved 2026-08-24