October 27, 2021

The transformation of grapes responsible for Sauternes wines

 Botrytis Cinerea develops with difficulty and we are witnessing an evolution of berries passing through two stages: The stage "rotten full" characterized by purplish discoloration of berries: the whole bay is contaminated but retains its volume. The "rotten rotten" stage where the berry wilts, there is loss of water by drip (60% of the total volume) because the film has become porous: the mushroom has digested the skin! At this point, the concentration of all elements is maximum.

This stage is sought after but difficult to obtain. It is very dependent on the climatic conditions: if it is too wet, the mushroom grows a lot and consumes more sugars. The volume of the berries increases and the concentration decreases.

When climatic conditions are good, despite the consumption of the mushroom, we observe an increase in the concentration of sugars and acids through evaporation through the film became porous: musts (liquid product obtained after pressing or crushing from fresh grapes In the context of European legislation, the must must have an alcohol content of less than 1 ° .This is unfermented grape juice.
) can reach 350 g / l of sugar. For the same reason, the increase in concentrations of potassium, calcium and magnesium ions is observed.

Glycerol formation (The most abundant constituent of wine after water and ethyl alcohol) With its sweet taste, equal to that of glucose, glycerol makes a modest contribution to the mellowness of wine.
) by the fungus (of the order of a few grams per liter in the roasted berry) provides a sweet flavor comparable to that of glucose, but is not degraded during fermentation. In addition, glycerol is responsible for the fixation of specific flavors in Sauternes.

The sweet wines will particularly benefit from the formation of pleasant aromas of honey, spices, candied fruit, orange peel, linden, tea, mint, pepper or sandalwood, ... .

Learn more
Château Guiraud 1st Grand Cru classé - //www.chateau-guiraud.fr

White wine | Wikipedia audio article (October 2021)