Why Is There Sugar in Wine?

Why is there sugar in wine?
Sugar in wine mainly comes from the grapes, glucose and fructose which accumulate during ripening.
During alcoholic fermentation yeasts convert most of it into alcohol. The sugar that remains is called residual sugar, it defines whether a wine is dry, off-dry or sweet, like Sauternes.
Sugars in wine are important because they influence the taste and balance of a wine, adding sweetness, roundness, and balancing acidity and tannins in both whites and reds.
They also influence wine style and typicity, with dry wines being light, crisp, often sharp, off-dry wines fruitier, rounder and smoother, and sweet wines, like Sauternes, more complex, deep and capable of aging well. They are also important during fermentation and aging, especially for sweet wines, where a small amount of residual sugar can improve a wine’s aging ability and increase its complexity.
Sugars also play a key role in sparkling wines. After the first fermentation, winemakers add the liqueur de tirage, wine and sugar to trigger the prise de mousse, the second fermentation that creates the bubbles. Later, during disgorgement, a final dosage is added to adjust the final taste. This creates different styles of sparkling wine, with Brut Nature having no added sugar, Brut with less than 12 grams of sugar, and Demi-Sec between 30 and 50 grams of sugar. Even a few grams can change the entire experience of a sparkling wine.
In conclusion, sugar in wine is not just a question of taste. It is an essential element that shapes the style, balance and overall quality of our wines.