The general classifications of dessert wine and fortified wine refer to different concepts; however, many wines can fall under both classifications. While nearly all fortified wines could be called dessert wines, not all dessert wines are fortified.
Fortified wines are generally made by adding distilled spirits, typically clear grape spirits — also called clear brandy — to wine. These spirits increase the alcohol content of the wine, or “fortify” the wine, typically resulting in a finished product with between 16 and 20 percent alcohol by volume. Generally the spirits are added to the wine to stop the process of fermentation, leaving unfermented sugars in the wine and thus increasing the sweetness of the finished wine. Examples of fortified wines include port, sherry, Madeira and vin doux naturels.
The term dessert wine has a number of different definitions. Generally, however, the term means a wine often drunk with dessert, a sweet wine that is nearly a dessert itself, a wine drunk after the main meal, or even a wine drunk after dessert. In the United States, a table wine, at least according to the regulations set forth by the Bureau of Alcohol, Tobacco and Firearms, is a wine with no more than 14 percent alcohol by volume. Dessert wines, by contrast, have alcoholic content above 14 percent but less than 24 percent by volume. Regardless of the specific definition, dessert wines almost always have one thing in common: significantly more sweetness than table wines.
Ways of Making Sweet Wines
Fortifying is one way to make a sweet wine, but there four other traditional methods as well. In one method, grapes are allowed to hang on the vine until after traditional harvest time, allowing the sugar to increase in the grapes before harvesting. These types of wines are generally called “late harvest” wines.
With the second method, grapes are picked at a more traditional time, but then laid out on mats or trays to “raisinate”-- or dry out. This raisination concentrates the sugar in the grapes, resulting in a sweeter wine. Typical examples of this type of wine include vin santo from Italy and strohwein from Austria.
With the third method, grapes are allowed to freeze on the vine itself. By allowing the grapes to freeze, the vintner can partially separate the water in the grape from the more sugary juices. What is left behind is a wine with exceptional sweetness and a light, syrupy consistency. Examples of this type of wine include eiswein and vin glace.
The final method some vintners use to create sweet wines, is to allow the grapes to be attacked by what is known as "noble rot." Noble rot stems from a particular type of fungal infection in grapes that concentrates the sugars. Examples of traditional sweet wines utilizing noble rot include French Sauternes, Tokaji aszú from Hungary and trockenbeerenauslese from Germany.
Noble Rot Explained
Botrytis cinerea is a grey fungus that can infect grapes in moist conditions. Generally, winemakers try to control and eliminate this fungus as it can result in serious crop loss. However, in some parts of the world, under the right conditions, Botrytis cinerea creates a beneficial condition called "noble rot." With noble rot, the Botrytis cinerea fungus consumes a significant portion of the water in the grapes and concentrates the sugars, resulting in a sweet, syrupy wine.
- The Wine Bible; Karen MacNeil
- Windows on the World Wine Course; Kevin Zraley
- Electronic Code of Federal Regulations, Title 27: Alcohol, Tobacco and Firearms: Part 4 — Labeling and Advertising of Wine
- Institut National de la Recherche Agronomique: Botrytis Genome Sequencing Project
- Photo Credit Ralph Orlowski/Getty Images News/Getty Images