Sauternes is primarily made from Sémillon (usually about 80%) followed by Sauvignon Blanc and then Muscadelle. Alcohol content must be at least 13% and is usually 14% with substantial residual sugars (8-14g/100g). The distinct character of the sweet wines from Sauternes primarily comes from the noble rot or botrytis infections that occur regularly in the vineyards of the region. Botrytis infection causes concentration of sugar and tartaric acid as well as stimulating production of glycerol which gives a high viscosity to the resulting wine. Botrytis also greatly increases the complexity of the resulting wines.