Glossary · Fruit
Starch-iodine test
Definition
A field test for ripeness in which a cut apple is stained with iodine solution: starch turns blue-black, so the extent of the unstained area shows how far starch has converted to sugar.
- Subject
- Fruit
In more detail
The test is read against a printed index of patterns rather than as a single number, and each cultivar has its own typical progression. It is more useful for judging picking date in an intensive orchard than for traditional cider fruit gathered from the ground, where sweating continues the conversion after harvest.
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.
Fruit
Ripeness
The stage at which fruit has completed starch conversion, reached its characteristic sugar and softened enough to press. For cider fruit it is judged later than for dessert fruit, often at or after natural drop.
Fruit
Sweating
Holding harvested fruit in a heap or a shed for days or weeks before milling, so that starch converts to sugar, flesh softens and moisture is lost.
Chemistry
Specific gravity
The density of a liquid relative to water at the same temperature. In cider it is the routine measure of dissolved sugar before fermentation and of progress during it.
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.
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.
NIAB (incorporating East Malling Research)
NIAB · research institute · retrieved 2026-08-24
East Malling developed the M-series apple rootstocks that determine tree size in essentially every modern orchard, cider orchards included. The authority CiderHQ uses for rootstock behaviour.