Noble rot

Introduction

Noble rot, also known as Botrytis cinerea, is a type of fungus that affects grapes and some other fruits. It is beneficial in the production of certain types of dessert wines, where it contributes to the unique flavor and aroma characteristics. The fungus causes the grapes to shrivel, concentrating the sugars and flavors, which results in a sweet, complex wine.

Biology of Noble Rot

The Botrytis cinerea fungus is a member of the Sclerotiniaceae family. It is a necrotrophic fungus that affects many plant species, although its most notable host is the grapevine. The fungus requires specific conditions to develop, including high humidity followed by dry conditions. This is why noble rot is typically associated with certain wine regions that have these specific climatic conditions, such as Sauternes in France and Tokaj in Hungary.

A close-up of a grape cluster affected by noble rot. The grapes are shriveled and covered with a grayish-white mold.

Effect on Grapes

When noble rot affects grape clusters, it causes the grapes to partially dehydrate, resulting in concentrated sugars and flavors. This process, known as raisinization, is what gives wines made from these grapes their distinctive sweet taste. The fungus also produces an enzyme that breaks down the grape skin, allowing water to evaporate more easily and further concentrating the grape's contents.

Production of Noble Rot Wines

The production of noble rot wines is a labor-intensive process. The grapes must be hand-harvested, often in several passes, to ensure that only the grapes affected by noble rot are selected. The timing of the harvest is critical, as the grapes must be picked at the precise moment when the balance between sugar and acidity is optimal. After harvest, the grapes are typically pressed immediately to extract the sweet, concentrated juice.

Regions Known for Noble Rot Wines

Several wine regions around the world are known for their noble rot wines. These include the Sauternes and Barsac regions in Bordeaux, France, the Tokaj region in Hungary, and the Rheingau and Mosel regions in Germany. In the United States, noble rot wines are produced in parts of California and Oregon.

Notable Noble Rot Wines

Some of the most famous noble rot wines include Château d'Yquem from Sauternes, Tokaji Aszú from Hungary, and Trockenbeerenauslese from Germany. These wines are renowned for their complexity, longevity, and unique flavor profiles, which can include notes of honey, apricot, and dried fruit, along with a characteristic botrytis aroma often described as reminiscent of mushrooms or damp forest floor.