What is Botrytis or 'Noble Rot' in Wine?
Noble Rot, also known by its technical term, "Botrytis Cinerea," is a beneficial mold or fruit fungus that causes grapes to shrivel and the fruit to dehydrate. This causes a deep concentration of flavors, sugar and acid in the fruit. Noble Rot really doesn’t sound like a term that would be associated with the enjoyment of wine. However, in some instances, it can be very beneficial when producing high alcohol or sweet wines. Some of the best dessert wines are made from these grapes including Sauternes and late-harvest Rieslings.
The Noble Rot fungus is prevalent in high moisture and humid climates. It begins with a spore that lands on the grapes and germinates when the grapes remain wet for several hours.
Winemakers will often encourage Botrytis in the vineyard to produce sweet wines, but it’s a tricky business. If the grapes remain too wet after they have been infected, they will turn to gray rot, which is nothing more than rotten, unusable fruit. If the weather stays drier after infection, the fruit will shrivel and dehydrate but will keep the same sugar content, which is ideal in the production of sweet, high alcohol wines. And because the fruit is concentrated, it takes more Noble Rot grapes to produce the desired wines.
Botrytis fruit will often have sweet, honey and spice notes, making it the perfect fruit for making pleasing after dinner dessert wines.