residual sugar (RS)

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The natural grape sugar that is either unfermented at the end of the FERMENTATION process or added back into the wine, as with a DOSAGE added to a SPARKLING WINE. In some cases, there is so much natural sugar that fermentation can’t complete its process, as is the case with some DESSERT WINES like Germany’s TROKENBEERENAUSLESE. In other instances, fermentation is purposefully arrested by adding a soupçon of SULFUR DIOXIDE, which inhibits the yeast, or by adding ALCOHOL (as is done with FORTIFIED WINES), which raises the alcohol to a level (15 to 16 percent) above which the YEAST cannot work. DRY wines may have little residual sugar (0.1 to 0.2 percent), semisweet wines usually range from 1 to 3 percent, and LATE HARVEST wines may range as high as 28 to 30 percent. Residual sugar is sometimes referred to as reducing sugar or by the initials RS.