Noble rot

Botrytis cinerea , agent of gray rot (figures 1 and 2), is capable under certain climatic and water supply conditions of the vine to develop in a particular form called " noble rot ". The latter is at the origin of great syrupy white wines French , in particular those of the South-West (Montbazillac, Sauternes) made from Sémillon (figures 3 to 7) and sauvignon (figures 8 to 17), or selections of grains. noble Chenin de Loire or even Gewurztraminer, Pinot Gris and Riesling d'Alsace. It is also associated with certain German, Austrian, Hungarian or Swiss productions in Europe.


We know that the first condition for establishing "noble rot" is its intervention on perfectly ripe and healthy berries. The particular development of this fungus is favorably influenced by daily alternations of wet and dry periods. Moisture, favoring fungal proliferation, is provided by morning mists, while sunny and windy afternoons facilitate concentration by evaporation of water through the film which has become permeable.


Before this botrytization process , the grape berries are golden, with thick skin, slightly pigmented with brown. Under the action of Botrytis , they then take a chocolate brown hue, then turn purple or even midnight blue before wilting. We then say that the grape is "roasted". These transformations are due to a significant loss of water, but also to an intense enzymatic maceration of their skin. By way of example, remember that the pectinase activity observed in a rotten berry is about a hundred times greater than that measured in a healthy berry.


In the end, these wines, obtained by careful and successive harvests of “noble grains”, are characterized by intense fruity flavors such as apricot, citrus or tropical fruit, which also have the characteristic of strengthening with aging. In the mouth, it is the perfect balance between the sweet liquor and the acidity that marks these great sweet wines which can defy time by their capacity of evolution under glass.