Noble Rot
The beneficial form of Botrytis cinerea fungus that dehydrates grapes, concentrating sugars and adding complex honeyed and apricot flavours essential to great sweet wines.
In depth
Noble rot (pourriture noble in French, Edelfäule in German) occurs when the Botrytis cinerea fungus attacks ripe grapes under specific climatic conditions: morning mists followed by warm, dry afternoons. This allows the fungus to penetrate grape skins without causing total rot, instead causing controlled dehydration.
As water evaporates from the infected berries, sugars, acids, and flavour compounds become concentrated. The fungus also produces glycerol and specific aromatic compounds — including sotolon (curry, fenugreek) — that give nobly rotted wines their distinctive character: honeyed richness, apricot, orange peel, and complex tertiary aromas.
The world's greatest naturally sweet wines depend on noble rot: Sauternes (France), Tokaji Aszú (Hungary), Trockenbeerenauslese (Germany and Austria), and Coteaux du Layon (Loire Valley). The labour-intensive harvesting — pickers must select individual infected berries by hand over multiple passes through the vineyard — makes these wines expensive to produce.
Distinguish noble rot from grey rot (pourriture grise), the destructive form of the same fungus that damages grapes without concentration. Grey rot dilutes quality; noble rot enhances it.
Related exam topics
Frequently asked questions
- What is the difference between noble rot and grey rot?
- Both are caused by the same Botrytis cinerea fungus. Noble rot occurs under specific dry conditions after morning mists, dehydrating grapes and concentrating sugars to produce great sweet wines. Grey rot occurs in wet conditions, causing destructive rotting that dilutes flavour and ruins the harvest.
- Which wines are made from noble rot grapes?
- The most famous noble rot wines are Sauternes from Bordeaux (made from Sémillon and Sauvignon Blanc), Tokaji Aszú from Hungary (Furmint), Trockenbeerenauslese from Germany and Austria (Riesling), and Quarts de Chaume / Bonnezeaux from the Loire Valley (Chenin Blanc).
Practise questions on this topic
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