After fermentation, fruit sugar can remain in the wine, because the yeasts are no longer effective, or because the fermentation was artificially interrupted. This is referred as residual sugar. Depending on the proportion of residual sugar the wine is called dry, semi-dry, half-dry or sweet.
The flavour of wine is not only dependending on residual sugar. The aromas of the grape variety, the cultivation in the vineyard and the expansion in the wine cellar contribute to the individual aromas of a wine. An important flavor factor in the wine is the harmony of tartaric acid, residual sugar and alcohol content. A dry wine with high alcohol content can taste mild, while sweet wines with a high acidity often appear semi-dry. For red wines, the vegetable tannins from the grape bowl and the kernels also play an important role.
The term "mild" is used for low-acid wines or for sweet wines with a residual sugar content of more than 46 g / l, in which acid falls into the background.
Dry is not the same as sour.
Dry is the name for wines that are fermented almost completely or completely, that is for wines with a residual sugar content not exceeding 4 grams per liter. The legislature allowed the designation dry in addition to a residual sugar content of 9 grams when expressed in g / l tartaric acid total acidity than 2 g / l is lower than the residual sugar content (formula: acid + 2 up to the limit 9).
Very dry, acidic white wines or tannin-stressed, astringent red wines are commonly referred to as "herb". The term comes from the sparkling wine production and is there just as legally defined as the term "brut".
Wines with a residual sweetness of more than 9 grams per liter are referred to as "fruity" because the sensory perceptible sweetness corresponds to the sweetness of the grape.
Half-dry wines may have up to 12 grams of residual sugar per liter, or up to 18 g / l when doing the residual sugar content not exceeding the acidity than 10g. (Formula: acid + 10 up to the limit 18). Semi-dry is a term for the taste of wines containing more residual sugar than half-dry wines, but which are not sweet.
Sweet wines have a higher residual sweetness than semi-sweet wines, but not more than 45 g / l.
The declaration extra sweet for wines is allowed from 45 g / l residual sweetness.