Also known as residual sweetness (RS), the amount of sugar in wine that is preserved by a natural end to fermentation or by a deliberate stop. The latter can be achieved in various ways such as cooling or by adding sulphur or alcohol. The residual sugar consists mainly of fructose (fruit sugar), because glucose (grape sugar) is converted more quickly into alcohol and carbon dioxide, and to a small extent of non-fermentable sugars (pentoses). The remaining sugar content (dry to sweet) can be indicated optionally on the label according to wine law. The phenomenon that the subjective perception of sweetness in wine can differ relatively strongly from the actual analytical values, especially with high acidity, is described under sweet.