Dessert wines can be made in a variety of different ways. In most cases, the high residual sugar of dessert wines is the result of “noble rot.” Grapes are attacked by the Botrytis cinera fungus and left on the vine to become overly ripe. As the fungus draws water out of the grape, the grape becomes super infused with flavor and develops a high concentration of sugar. This is the method by which Sauternes from France and Tokaji from Hungary are made. Some common flavor notes of Sauternes include apricots, honey, peaches and nuttiness. Apricot and honey predominate in Tokaji as well.
Another way in which wine grapes become super infused with sugar is by simply picking the grape later than usual. This is the case with Beerenauslese and Trokenbeerenauslese. The grapes can also be allowed to freeze on the vines. Eiswine (Icewine in Canada) is produced in this manner. All of the previously mentioned wines are normally made with Riesling grapes. These wines tend to have super intense flavors of peach, honey, and, at times, apple.
Any grape can be harvested late and made into a dessert wine. Late harvesting of the grape allows for more intense flavors and imparts a sweeter taste. Late Harvest Sauvignon Blanc still has notes of passion fruit and citrus, but the flavors are more powerful and tend to have a honeyed note to them. Late Harvest Zinfandel has incredibly strong flavors of raspberry and chocolate.