Noble rot is a beneficial form of infection caused by the fungus Botrytis cinerea under specific vineyard weather conditions. It affects ripe, healthy grapes and causes them to lose water, concentrating sugars, acids and flavour compounds. Noble rot is essential to the production of several famous sweet wines, including Sauternes, Tokaji Aszú and German Beerenauslese and Trockenbeerenauslese.
Noble rot typically develops when humid or misty mornings encourage Botrytis infection, followed by dry, sunny or breezy afternoons that allow the berries to dehydrate rather than decay. The balance is delicate: prolonged wet conditions can cause destructive grey rot, while unsuitable weather may prevent noble rot from developing.
As the berries shrivel, sugar and flavour compounds become concentrated. Botrytis can also contribute distinctive aromas and flavours such as honey, apricot, marmalade, saffron, dried fruit and spice. Acidity is important to balance the concentrated sweetness. The effect varies by grape variety, vintage and degree of botrytisation.
Harvest is often carried out in several selective passes, with pickers choosing individual berries or bunches at the desired stage of concentration. Yields are low and the process is labour-intensive. The grapes are then pressed and fermented under controlled conditions, often producing wines with high residual sugar and significant acidity.
Example: Sauternes producers in Bordeaux select botrytised Sémillon, Sauvignon Blanc and Muscadelle grapes for concentrated sweet wine.
Noble rot develops when conditions allow controlled dehydration and concentration of healthy ripe berries. Grey rot develops under persistently wet conditions and can spoil grapes, producing undesirable flavours and losses.
Chef’s note: noble rot wines can pair with foie gras, blue cheese, fruit desserts and selected spicy dishes. Their sweetness should be balanced by acidity and the intensity of the food.
This term is one of hundreds covered in depth across OCS courses, learning paths, and 1-on-1 coaching with Chef Eric.
