Noble rot

Fungal infection beneficial to winemaking

Noble rot is a beneficial form of grape infection caused by the fungus Botrytis cinerea. This process is crucial in the production of some of the world's most celebrated sweet wines. Unlike its destructive counterpart, grey rot, noble rot can enhance the flavor and complexity of wines by concentrating sugars and acids in the grapes.

Process

Botrytis-infected Riesling grapes

Noble rot occurs under specific climatic conditions, typically in regions with misty mornings followed by warm, dry afternoons. The fungus attacks the grape skins, causing them to shrivel and dehydrate. This dehydration concentrates the sugars, acids, and flavors within the grape, leading to a more intense and complex wine.

The process begins when Botrytis cinerea spores land on the grape skin. The fungus penetrates the skin, drawing out moisture and leaving behind a higher concentration of sugar and other compounds. The grapes take on a shriveled appearance, and their flavors become more concentrated.

Impact on Wine

Botrytis-infected Sémillon grapes

Wines made from botrytized grapes are known for their rich, honeyed flavors and complex aromas. The concentration of sugars and acids results in a sweet wine with balanced acidity, preventing it from being cloying. Common flavor notes include honey, apricot, peach, and citrus.

Noble rot is essential in the production of several renowned wines, including Sauternes from France, Tokaji from Hungary, and Trockenbeerenauslese from Germany. Each of these wines showcases the unique characteristics imparted by the noble rot process.

Regions

Noble rot is most commonly associated with specific wine regions where the climate supports its development. In Bordeaux, the Sauternes region is famous for its botrytized wines, primarily using Sémillon, Sauvignon Blanc, and Muscadelle grapes. The Loire Valley also produces notable botrytized wines, such as Coteaux du Layon.

In Hungary, the Tokaj region is renowned for its Tokaji Aszú wines, made from grapes affected by noble rot. The unique climate of the region, with its morning mists and sunny afternoons, is ideal for the development of Botrytis cinerea.

Winemaking Techniques

The production of noble rot wines requires careful vineyard management and winemaking techniques. Grapes are often hand-harvested in multiple passes, selecting only those affected by the fungus. This labor-intensive process ensures that only the best grapes are used.

In the winery, the botrytized grapes are gently pressed to extract the concentrated juice. Fermentation is typically slow, as the high sugar content can inhibit yeast activity. The resulting wine is aged in barrels to develop its complex flavors and aromas.

Related pages

• Sauternes (wine)
• Tokaji
• Trockenbeerenauslese
• Botrytis cinerea