Concept card Method
Raisining and noble rot
In one sentence
Two ways of concentrating the grape's sugar before fermentation by taking water out of it: letting it dry, or letting botrytis pierce its skin.
From ripe grape to sweet wine
A ripe grape
The starting point: the vine has made its sugar.
Water is lost
The grape dries, on the vine or after picking, or botrytis pierces its skin.
A sweeter must
Sweet Jurançon: at least 247 g of sugar per litre of must (Petit Manseng).
A sweet wine
Fermentation stops before converting everything: some sugar remains.
Key points
- Raisining: the grape loses water and shrivels, on the vine or after picking.
- Noble rot: Botrytis cinerea pierces the grape's skin; water evaporates and the sugar concentrates.
- Botrytis turns noble when damp mornings let it take hold and dry afternoons hold it back.
- They are not the only routes: for ice wine, part of the water stays frozen at pressing.
What it changes in the glass
- Botrytis does more than concentrate: it leaves the wine characters that a merely dried grape lacks.
- Raisining concentrates the grape with no fungus involved, so it leaves no botrytis characters.
Not to be confused with…
It works in the vat: added spirit stops the fermentation. Raisining and botrytis act earlier, on the grape.
Grey rot
The same fungus when nothing holds it back: it ruins the crop instead of concentrating it.
For a vin de paille, healthy grapes are picked, then left to dry for six weeks, with no fungus. How does this fruit get concentrated?
One question to test yourself: it does not count towards your progress.
Drying on the vine: Jurançon
Jurançon makes its sweet wines without relying on the fungus. Its specification explains why: its grapes have thick skins and resist grey rot well, and in autumn a southerly foehn wind brings warmth and dry air.
247 g/L
of sugar at least for Petit Manseng in a sweet Jurançon, against 230 for the others
281 g/L
at least for the "vendanges tardives" term
- Drying the fruit off the vine is forbidden there, unless it is done in the heart of the plot.
- Late-harvest Petit and Gros Manseng may be picked only from 2 November.
Drying after picking
- Vin de paille comes from grapes picked and then left to dry: at least six weeks in Arbois, at least 45 days in Hermitage.
- The term is therefore not unique to the Jura.
The fungus: Sauternes
Botrytis cinerea is the same organism as grey rot. In Sauternes, the cold Ciron flows into the warmer Garonne and lays down the autumn morning mists in which it develops.
- It does not spread everywhere at the same pace: pickers make successive passes, taking only what is ready.
- Thin-skinned Sémillon is highly receptive to it; in the Loire, Chenin Blanc also makes botrytised sweet wines.
- A year without the alternation of damp and dry gives no botrytis, or the wrong kind of rot.
The cold: ice wine
Under the OIV definition, the grapes are frozen when harvested and pressed while still frozen, at a recommended temperature of −7 °C or below. Grapes frozen in a cold room do not count. It is an international definition, not a law.
Alsace, which names both
The Alsace specification names "concentration on the vine" and "the development of noble rot" side by side. It reserves neither route for a term: "vendanges tardives" and "sélection de grains nobles" differ, among other things, by sugar thresholds.
To learn it in depth
Related reading
Sources (7)
- Official sourceCahier des charges de l'appellation d'origine contrôlée « Jurançon »— Institut national de l'origine et de la qualité (INAO) / Ministère de l'agriculture
- Official sourceCahier des charges de l'appellation d'origine contrôlée « Alsace » ou « Vin d'Alsace »— Institut national de l'origine et de la qualité (INAO)
- Official sourceRésolution OENO 6/2003 — Definition of ice wine— Organisation internationale de la vigne et du vin (OIV)
- Official sourcePl@ntGrape — le catalogue des vignes cultivées en France— IFV, INRAE et Institut Agro Montpellier (UMT Géno-Vigne®)
- Official sourceArrêté du 25 mars 2026 homologuant le cahier des charges de l'AOC « Sauternes »— Légifrance — Journal officiel de la République française
- Official sourceCahier des charges de l'appellation d'origine contrôlée « Hermitage »— Institut national de l'origine et de la qualité (INAO)
- Official sourceCahier des charges de l'appellation d'origine protégée « Arbois »— INAO / Ministère de l'agriculture (Bulletin officiel)