How does wine become sweet? Aszú, late harvest, ice wine, straw wine
The shared secret of sweet wines is that the sugar content of the grape berry becomes concentrated before or after harvest. This can happen through noble rot, shrivelling, freezing or drying.
Four routes to sweetness
What happens to the grapes? | What wine does it make? |
|---|---|
Noble rot (Botrytis cinerea) | Tokaji aszú, Tokaji eszencia |
Shrivelling on the vine, late harvest | late-harvest wine |
Freezing on the vine | ice wine |
Drying on straw or racks | straw wine, passito |
How does it become a sweet wine?
Water evaporates from the grapes or freezes out, so sugar, acidity and aroma become more concentrated. During fermentation the yeast cannot turn all the sugar into alcohol, and the remaining sugar makes the wine sweet. Exactly how sweet is shown by the amount of residual sugar (g/l); the categories are described in the article “Dry, off-dry, medium-sweet, sweet: how wines are classified by sugar content”.
