Residual sugar
/rɪˈzɪdʒuəl ˈʃʊɡər/
Residual sugar /rɪˈzɪdʒuəl ˈʃʊɡər/ is the natural grape sugar that remains in a wine after alcoholic fermentation has finished or been stopped, usually measured in grams per liter (g/L). It is a key technical parameter that largely determines how dry or sweet a wine tastes, though its perception is also influenced by acidity, alcohol, and other structural elements.
Examples
- A Mosel Riesling with 7 g/L residual sugar and high acidity may taste nearly dry, even though the RS is above the level of many very dry wines.
- A Moscato with 45 g/L residual sugar will taste clearly sweet and is often marketed as a medium-sweet or sweet white wine.
- A Sauternes or Tokaji Aszú dessert wine can have well over 100 g/L residual sugar, giving a lusciously sweet, viscous texture balanced by high acidity.
Etymology
The expression "residual sugar" is an English technical compound. "Residual" derives from Late Latin "residuum" (that which remains behind), from Latin "residere" (to remain, sit back), and in English has been used since the 17th century to mean what is left after a process is complete. "Sugar" comes via Middle English from Old French "sucre," Medieval Latin "succarum," Arabic "sukkar," Persian "shakar," ultimately from Sanskrit "śarkarā" (gravel, granulated sugar). As a wine-technical term, "residual sugar" entered English oenological and analytical chemistry literature in the late 19th to early 20th century, paralleling the rise of laboratory methods to quantify sugar in must and finished wine. It corresponds to terms like German "Restzucker" and is now a standard analytical and regulatory parameter in global wine practice.