What is Noble Rot?

NOBLE ROT OR BOTRYTIS?

Noble rot, as its name suggests, has something distinguished, majestic, noble about it! This type of rot, unlike grey rot which destroys plants, is on the contrary beneficial for the grapes. Botrytis Cinerea is the scientific name of this fungus that develops on grape berries. This fungus is actually responsible for both types of rot: grey and noble rot. In the wine world, the terms botrytis or botrytised grape always refer to noble rot, which is the cause of sweet wines with a particularly high sweetness.

THE MAGIC OF THE BOTRYTIS CINEREA

In autumn, when temperatures tend to cool down, a fungus called botrytis cinerea forms on the grape skin. At this stage, the grapes are already perfectly ripe and healthy. The botrytis fungus settles on an overripe berry. Microscopic filaments penetrate the grape skin. Depending on the thickness of the skin, botrytis settles in more or less easily. The skin of the grape is then covered with tiny holes, making the film porous. Thanks to warm, dry afternoons, the water inside the berry slowly evaporates, concentrating the acid, flavour and sugar in the grapes. The fungus acts as a natural concentrating agent.

VENDANGES TARDIVES AND SÉLECTION DE GRAINS NOBLES

The results of the action of noble rot on the grape berry are quite surprising, delicious and some would even say miraculous! However, this beauty of nature has its share of difficulties. Indeed, the rot does not develop uniformly on the bunch. The grapes may be in different stages of development. Before the process begins, the grapes are golden in colour, with their thick skins slightly pigmented with brown. Once attacked by the fungus, they turn brown, then chocolate, and finally purple or even blue, before wilting. These colour changes are due to a significant loss of water caused by evaporation. The wilted and differently coloured grape is then referred to as pourri plein stage or pourri rôti stage.

Several names indicate that a sweet wine is made from botrytised grapes. Vendanges Tardives and Sélections de Grains Nobles, which are found mainly in Alsace, indicate in their title the type of harvest carried out and therefore the style of wine. Indeed, for the fungus to develop on the grapes, the bunch must be able to remain on the vine beyond its ripening stage. This is why we speak of a late harvest. It is on overripe grapes that botrytis settles and develops. However, the fungus does not necessarily develop on all late harvest grapes. Some of the grapes may indeed be botrytised, others will not, or at least at different stages. The fact that the grapes are harvested late and therefore over-ripe allows the juice to be concentrated.

Since the rot does not develop uniformly on the bunch, several selections are necessary. These successive selections are made by hand, in order to select the best grapes, the fully botrytised berries with which the sweet wines will be made. Several visits to the vineyards are necessary, as the grapes on the bunch change day by day, week by week. The successive selections are generally made from September to November. This is why the Alsatians add the term 'Sélection de Grains Nobles' to their wines made from 100% botrytised grapes.

TRIE OR TRI?

The French terms trie and tri can be confusing as they do not have the same definition! While both refer to the world of viticulture and more particularly to the harvest, be careful not to confuse them. The word trie is a specific vocabulary used for sorting and harvesting the botrytised grapes. It refers to the different tries or passages in the vineyards during harvest, the aim of which is to select only the grapes properly affected by noble rot. The term tri refers to the sorting of the best berries for making a wine, discarding those of inferior quality. This work is often done in the cellar.

AT THE ORIGIN OF THE GREAT SWEET WHITE WINES

Noble rot is the element at the origin of the world's greatest sweet white wines. In France, the vineyards of Bordeaux, Alsace and the Loire Valley are the main regions producing sweet wines, which are produced by botrytis cinerea. The Sauternes, Barsac and Monbazillac, located in the Bordeaux and Dordogne regions, produce world-renowned nectars from the Sémillon and Sauvignon Blanc grapes. In Alsace, Vendanges Tardives and Sélections de Grains Nobles wines are made from Riesling, Gewürztraminer and Pinot Blanc. The Loire Valley, with its river running through the entire wine-growing area, produces sweet wines from the Chenin Blanc grape. The Coteaux-du-Layon, Bonnezeaux, Coteaux-de-Saumur and Quarts-de-Chaume are sweet white wines made from botrytis.

HUNGARIAN TOKAJI AND GERMAN SWEET WINES

However, France is not alone in producing these sweet botrytised nectars. Hungary is particularly famous for its Tokaji wine made from the local Furmint grape. This sweet white wine, called Tokaji, produced on the border between Hungary and Slovakia, was once called 'the wine of kings'. Indeed, the Hungarians are said to have sent several barrels of wine to Louis XIV, who was fond of it! This Tokaji wine was quickly invited to the great tables of the European courts, and was often offered as a diplomatic gift throughout the continent. Some claim that it is the oldest sweet wine in the world, with traces of it dating back to the 16th century.

Germany and Austria are two wine-producing countries where part of the production is also reserved for the production of sweet wines from botrytised berries. These are the Auslese wines, but above all the Beerenauslese and Trockenbeerenauslese.