as Süssreserve) or ordinary table sugar. Even among the driest wines, it is rare to find wines with a level of less than 1 g/L, due to the unfermentability of certain types of sugars, such as pentose. By contrast, any wine with over 45 g/L would be considered sweet, though many of the great sweet wines have levels much higher than this. For example, the great vintages of Château d'Yquem contain between 100 and 150 g/L of residual sugar. The sweetest form of the Tokaji, the Eszencia, contains over 450 g/L, with exceptional vintages registering 900 g/L. Such wines are balanced, keeping them from becoming cloyingly sweet, by carefully developed use of acidity. This means that the finest sweet wines are made with grape varieties that keep their acidity even at very high ripeness levels, such as Riesling and Chenin blanc. How sweet a wine will taste is also controlled by factors such as the acidity and alcohol levels, the amount of tannin present, and whether the wine is sparkling or not. A sweet wine such as a Vouvray can actually taste dry due to the high level of acidity. A dry wine can taste sweet if the alcohol level is elevated. Medium and sweet wines have a perception among many consumers of being of lower quality than dry wines. However, many of the world's great wines, such as those from Sauternes (including Barsac) or Tokaj, have a high level of residual sugar, which is carefully balanced with additional acidity to produce a harmonious result. Süssreserve Süssreserve (, literally "sweet reserve") is a wine term referring to a portion of selected unfermented grape must, free of microorganisms, to be added to wine as a sweetening component. This technique was developed in Germany and is used with German-style wines such as semi-sweet Riesling or Müller–Thurgau. The technique not only raises the sugar level of the wine, but also lowers the amount of alcohol. Under German law, no more than fifteen percent of the final wine's volume may be the reserved juice. This practice is allowed also for Prädikatswein, the highest level in the German wine classification. It is often used for semi-sweet Kabinett and Spätlese, but more rarely for Auslese and upward. The use of Süssreserve results in a different composition of sugars in the wine in comparison to residual sugar from arrested fermentation. Grape must contains mainly the sugars glucose