1. Fermentation stops before all the grape juice (known as the must) sugars have been converted to alcohol. For example, when the fermentation stops naturally before all the sugars have been converted, as is the case with very sweet musts such as those from Botrytis (noble rot) grapes (more on that in another Wine Word post) such as Tokaji Aszú, Sauternes, German or Austrian BA or TBA wines. Ice wines also fall into this category.
2. Fermentation is stopped (known as arrested) before all the sugars have been converted to alcohol to deliberately leave a certain amount of residual sugar. The fermentation can either be stopped by chilling the fermenting wine down to a very low temperature, at which the yeasts cannot function. This is the case with Asti and Prosecco wines as well as German Spätlese or Auslese wines and the sweeter styles of Vouvray from the Loire. Or, the fermenting wine can be arrested through fortification - i.e the addition of a spirit alcohol, which raises the alcohol level beyond which the yeasts can not function. Port and Madeira wines are key examples.
3. A wine gets sugar or a permitted sweetening agent added back into the finished dry wine. Most high-volume, lower end wines with a small amount of residual sugar are sweetened this way. White Zin falls into this category. Also, many under $10 Chardonnay wines contain up to 4-6 g/l
4. It's a sweet sherry wine. Contrary to popular belief, sherry wines are naturally dry. The wines are always fermented dry, then fortified, and then if destined for a sweet style, such as an Oloroso or Cream Sherry style, they are sweetened by the addition of PX (the very sweet Pedro Ximenez wine).
5. It's a Champagne and sparkling wine. Ever wonder what the term 'Brut' means on a Champagne or sparkling wine label? It is an indication of the style - a style based on the 'dosage' or residual sugar level in the wine. A brut style of wine can contain between 6g and 15g residual sugar/l. However, you rarely notice it because of the wine's high acidity. This residual sugar, called dosage is added just before corking.
Sweetness - Balance is Key
Sweet wines, or rather some of those termed off-dry, have suffered from a poor image in the past. But some of the greatest, longest lived wines in the world are sweet. That is because, as well as being sweet they also have very high acidity, which balances the high level of sugar.
Mary Gorman-McAdams, MW (Master of Wine), is a New York based wine educator, freelance writer and consultant.
Previous Wine Words:
• Wine Words: Length and Finish
• Wine Words: Minerality
• Wine Words: Acidity
• Wine Words: Tannin
• Wine Words: Body
• Wine Words: Alcohol
• Wine Words: Aromas
• Wine Words: Texture
• Wine Words: Complexity
(Image: Underlying image by Sadovnikova Olga/Shutterstock)