What is the definition of residual sugar in wine?

Residual sugar in wine refers specifically to the amount of sugar that remains in the wine after fermentation has been completed. During the fermentation process, yeast converts the sugars in the grape juice into alcohol and carbon dioxide. However, if the fermentation is stopped before all the sugar is converted into alcohol, some sugar will remain in the wine. This leftover sugar is what is measured as residual sugar, and it significantly impacts the wine’s sweetness and overall profile.

Understanding residual sugar is essential for wine tasting and pairing, as it influences the perception of sweetness, balance, and mouthfeel in the wine. It can also differentiate styles, such as dry wines with low residual sugar versus sweeter wines with higher residual sugar.