Wines that are high in both sugar and acidity, such as Sauternes, are ‘incredibly long-lived’
Ask Decanter
Each month our experts answer your burning wine questions. Email your queries to [email protected]
SWEET MYSTERY
How does a wine’s residual sugar level affect its ageing potential?
Michael Sunderland, by email
Anne Krebiehl MW replies: This is a question that immediately begs another: how much sugar? Wines can be bone dry with less than 1g/L of residual sugar, tooth-breakingly sweet with more than 300g/L and anywhere in between. At which point this sugar starts to help ageability isn’t clear-cut as other elements, such as alcohol level and concentration, also come into play. However, even at lower levels, like for instance in the dosage of sparkling wines to brut level (that is, up to 12g/L of sugar), there’s anecdotal evidence that this small amount of sugar helps the wine to age.
Sugar at higher levels definitely acts as a preservative because sugar absorbs water, increases osmotic pressure and thereby limits the bacteria that need water to thrive. This is why fruit can be preserved in sugar. Very sweet wines are thus incredibly long-lived.
Wines in which not only sugar but also acidity is high, such as Sauternes, Riesling trockenbeerenauslese and other nobly sweet styles, are almost eternal because the preservative effect of sugar, combined with that of alcohol and acid, is potentiated. The longest-lived wines are either sweet and fortified, such as Madeira, or incredibly concentrated, very sweet, botrytised wines.
THE WORD ON WOOD
What’s the difference between French and American oak?
Sam Carter, by email
Oak is widely used in the winemaking process (during both fermentation and