restsuiker

Restsuiker, or residual sugar, is the amount of sugar that remains in wine after fermentation is complete. It is typically expressed in grams per liter (g/L). The level of restsuiker is determined by how fully fermentation proceeds: yeast converts most grape sugar into alcohol, and fermentation may stop naturally or be halted intentionally, leaving some sugar unfermented. Factors such as grape ripeness, fermentation temperature, yeast strain, and deliberate sugar additions can influence the final RS.

Measurement and labeling of restsuiker are usually done by chemical analysis, often using enzymatic methods or chromatography. On wine labels, restsuiker may be reported as a specific g/L value or described with a sweetness category. Different markets use varying terms, but the concept remains the same: RS indicates the potential sweetness of the wine as perceived in the mouth.

Sensitivity to restsuiker depends on other components, especially acidity and alcohol. A wine with higher RS may taste sweeter, but high acidity can balance perceived sweetness, while higher alcohol can intensify warmth. Therefore, dryness classifications are not determined by RS alone, but by the interaction of RS with acidity and body.

Common sweetness ranges used in wine descriptions place restsuiker roughly as dry up to about 9 g/L, off-dry around 9–18 g/L, medium-sweet roughly 18–45 g/L, and sweet above about 45 g/L, though exact thresholds vary by region and producer. In practice, restsuiker helps define a wine’s style and pairing potential, from crisp, dry whites to lusciously sweet dessert wines.