Dessert wines are almost always sweet wines. The sweetness is produced by picking the grapes when they are very ripe and high in Brix or sugar (late harvest wines), stopping the fermentation through filtration, and/or stopping the fermentation by adding distilled spirits (fortified wines). The method of producing dessert wines also impacts the percentage alcohol, making dessert wines often either very low or very high in alcohol. Dessert wines often list the residual sugar percentage on the label in addition to the percentage alcohol.
Common Dessert Wines
Muscat – There are several different Muscat varietals, with the most popular being Muscat Blanc or Muscat Canelli. Other varietals include Orange Muscat and Black Muscat. The wines typically have a distinct, spicy aroma and flavor and are usually finished slight sweet to medium sweet. Some sweet fortified dessert wines are also made from the various Muscat varietals.
Port – A generic name for fortified wine usually made from red wine grapes such as Zinfandel or Petite Sirah or Portuguese grapes. Most California ports tend to combine strong fruit flavor with a depth and richness providing long aging potential. There are four basic categories of port:
Vintage Port – Made from grapes from a single year (vintage), bottled within 2 years, and aged in the bottle. The most expensive ports from the best sites and vintage are not made every year. These wines can age 50 years or more.
Ruby Port – Made from lower-quality batches of wine which are aged in wood for at least 2 years. The wine is bottled while it still exhibits youth, fruitiness, and a bright red color.
Tawny Port – A port made from a blend of grapes from several different years (vintages). They can be aged in wood for as long as 40 years. The best tawny ports stipulate the time that they have matured (e.g. 10, 20, 30, 40 years)
White Port – Made from only white grapes, which makes it golden in color. It is produced the same way that red ports are produced and can be sweet or dry.
Sherry – Generic name for fortified wines styled after Spanish sherry, though only a few of the best follow the traditional, time-consuming solera system of aging. Most California sherries are fortified then heated to produce the characteristic oxidized flavors. Styles range from dry to extremely sweet.
Vermouth – White wine that has been fortified and flavored with various herbs and spices, used chiefly in mixed drinks.
Now determine the overall quality based on your own impression. You are the best judge of whether or not you enjoy a wine.