Residual Sugar in Wine

Residual sugar, or RS, is the measure of sugar present in the wine after fermentation. During fermentation yeast attacks sugar (Glucose + Fructose), and the by-product is CO2 and alcohol (our most favorite.) After this chemical reaction, the measure of fermentable sugars left over is residual sugar – usually expressed in grams per liter (g/L) or as a percentage of weight to volume (% RS.) For example, our Syrah contains 6 grams of sugar per liter or 0.6% residual sugar.

Residual sugar in wine may also result from the addition of unfermented ‘must’ (a technique practiced in Germany and known as Süssreserve – a process of adding unfermented grape juice) or ordinary table sugar added to the wine as a sweetening component.

Residual sugar also has an relationship with acidity, as they are on opposite sides of the spectrum. If the wine has sugar you will probably want strong acidity as well, otherwise the wine will taste syrupy. Certain high-acid wines, like Riesling, can be more tasty with a few extra grams of RS. It’s all about balance.

Varying levels of RS result in wine classifications from bone dry to very sweet. Most wines at Dalvino fall into the bone dry, dry and off-dry category because we do not add any sugar to sweeten our wine. Any residual sugar in our wines are sugars that are left over after fermentation.  Wines falling into the sweet to very sweet category are achieved by adding table sugar to the wine or stopping fermentation at the desired sugar level.