How It’s Made
When a winemaker decides to produce a sweet wine, he or she faces a dilemma: sugar is required to make the wine taste sweet, but the sugars in grape juice are converted into alcohol during fermentation.
Because of this, winemakers have devised several strategies for increasing the sugar levels in finished sweet wine. The simplest method involves allowing grapes to become overripe on the vine so that they have plenty of sugar to spare for both sweetness and alcohol.
Winemakers can also add sugar to a wine, either to the grape must prior to fermentation (a method known as chapitalization) or to the finished wine as unfermented grape juice (what the Germans call Süssreserve). Alcohol (typically brandy) can also be added during fermentation to arrest the conversion of sugars, a process known as fortification or mutage.
Finally, producers can dehydrate the grapes and thereby concentrate the sugar content of the remaining juice. This can be accomplished by air drying the grapes in warm climates and causing them to raisinate (the French call this passerillage and the Italians call it passito), freezing the grapes in colder climates to produce ice wine, or by means of a fungal infection endemic to damp climates called Botrytis cinera that desiccates the grapes with Noble Rot.
Wines to Know
The most famous example of late harvest wine is German Riesling, where grapes are ranked in quality according to their ripeness or must weight (i.e. the concentration of sugar in the juice). The Auslese (”late harvest”) designation indicates a high level of residual sugar and is generally considered superior in style.
The category of fortified wine includes Port, Sherry, Madeira, and Marsala, but many of these are dry in style – for sweetness, look to Pedro Ximenez Sherry from Spain or Malvasia from the island of Madeira.
The best example of a passito or “raisin” wine is Vin Santo from the Tuscany region of Italy, a name that translates to “holy wine.” It is made by drying the local Trebbiano and Malvasia grapes on straw mats and aging the resulting wine in small wooden casks to give it a tawny color.
As mentioned above, ice wine happens when grapes are left to freeze on the vine, causing the water in the juice to precipitate out of the solution. The best examples are German eiswein, which is typically made from Riesling, and Canadian ice wine, which is made from the Vidal grape.
The most legendary sweet wines of all are produced when the Botrytis cinera infects grape berries and saps them of moisture, imparting a honeyed, crème brûlée flavor in the process. The classic examples are Sauternes from the Bordeaux region of France (the producer Chateau d’Yquem ranks among the most expensive wines in the world), and Tokaji from Hungary, which locals call “the wine of kings, and the king of wines.” Tokaji Essencia is the sweetest wine produced today, containing over 200 grams of residual sugar per liter. This sweet wine is so rich and syrupy that it is traditionally consumed from a spoon, not a glass.
As a general rule, sweet wine is served at the end of a meal, either on its own or as an accompaniment to a dessert course. When used in the latter context, the wine should always be sweeter than the dish it is paired with, and should also complement the flavors of the dish.
Fruitier styles like Riesling and ice wine pair well with dishes like summer pudding, pavlova, and fruit pastries. Richer styles like Vin Santo and Pedro Ximenez sherry are delicious with biscotti, sticky toffee pudding, and caramel.
Noble rot wines like Sauternes and Tokaji are considered classic pairings with pineapple upside-down cake, crème brûlée, and foie gras.
Red dessert wines like Ruby Port do particularly well with chocolate, and almost any dessert wine will act as a sweet condiment to a range of cheeses.