Definition - What does Noble Rot mean?
Noble Rot is a condition that affects wine grapes, caused by the fungus Botrytis cinerea. It is one of the few fungal diseases that winemakers welcome into their vineyards, particularly those that produce sweet wines. Noble Rot dries out the grapes and leaves the juice and sugars concentrated, resulting in a highly sweetened and complex wine.
Common wines made from Noble Rot grapes include sauternes from Bordeaux and rieslings and trockenbeerenauslese from Germany.
WineFrog explains Noble Rot
Botrytis cinerea either occurs naturally or is brought into the vineyard and sprayed on ripened grapes, resulting in Noble Rot. The fungus penetrates through the grape skin, dehydrating the grape and concentrating the sugar. Conditions in the vineyard need to be near perfect for Noble Rot to succeed. Ideal conditions are foggy, moist mornings that are followed by hot and dry afternoons. Humidity plays a large role in whether Noble Rot can be managed. If high humidity levels are too prolonged and no dry weather occurs, the grape skins can split, inviting bacteria into the grape and Noble Rot will not take effect.
The process to make Noble Rot wines is long and complex. The grapes are stickier from the fungus so manual harvesting methods are necessary. Fermentation is slow because Botrytis cinerea kills yeast and winemakers must carefully monitor it. Also, the wine must undergo more frequent racking before bottling. Winemakers embrace the complicated effort it takes to produce Noble Rot wines because of the benefits.
- Sweeter wines - Noble Rot causes the grapes to shrivel, concentrating the juice while retaining the same sugar content. More grapes are needed to produce the correct amount of juice and the high level of sugars result in extraordinarily sweet wine.
- A complex of flavors - Noble Rot causes grapes to produce higher levels of phenylacetaldehyde, which gives off aromas of honey, beeswax and ginger.
- Ages well - Noble Rot wines are highly suitable for cellaring. The high sugar content has an anti-microbial effect that allows for prolonged aging.