Since dessert wines can be found all over the world, we thought we would shed some light on the various methods used to make these sweet treats. There are about as many production methods as there are varieties of dessert wines, but many can be broken down into these categories:

Late Harvest – Made by leaving the grapes hanging on the vine as long as possible in order to concentrate grape sugars. Examples of this method include late harvest German Rieslings (Auslesse, Beernauslese, Trokenbeernauslese).

Noble Rot (Botrytis) – Literally, Botrytis is a fungus that punctures holes in the skins of the grapes so that water evaporates even more from the fruit, leaving behind deep, concentrated sugars. Don’t worry, the wine itself shows no sign of actual mold or fungus, but the fruit can look pretty unseemly to the untrained eye. These make very complex and long-lived wines, like Sauternes (traditionally), which is made of botrysized Semillon. Other grapes that can be affected by "noble rot" are Chardonnay, Chenin Blanc, and Riesling. A few examples include Sauternes, Barsac, and Selection des Grains Nobles.

Freezing Grape Clusters – Grapes are picked while frozen on the vine and immediately pressed. The water in the grapes is trapped as ice and does not make its way into the wine. This traditional method is extremely labor-intensive and risky, which is why it can be so expensive. Alternatively, producers can cheat and employ freezers, where grapes are harvested, then frozen and pressed. But while this keeps the price in check, the wine loses all the intensity and complexity of grapes kept on the vine till the absolute last minute. Many eisweins (or ice wines) are made with Riesling or other high acid whites, like Chenin Blanc.

Fortified Wines – In Port or Port-styled wines (true Port is ONLY from Portugal!), the fermentation is arrested by the addition of a spirit (usually aguardente or brandy). Yeast is incapacitated by the suddenly high levels of alcohol and fermentation stops, leaving behind a lot of residual sugar. This results in a wine both sweet and high in alcohol.

Deliberate Raisining – Grapes are allowed to dry on the vine or on mats to concentrate the sugars and get rid of excess water. Examples of this are Vin Santo, Amarone (which isn’t really a dessert wine, but it’s darn good with flourless chocolate cake), and Passito.

Incomplete Fermentation — Fermentation here is stopped before the yeast converts all the sugars to alcohol. The result is a sweet wine with low alcohol content, like Moscato d’Asti and some Rieslings.

What’s with the small bottles?
Dessert wines, from late harvest Rieslings to eiswein to Sauternes, most often come in smaller bottles, usually 500ml or 375ml. Smaller servings are standard, as these are usually rich, decadent treats rather than quaffing wines.

Dessert wines are also very difficult and risky to make. For example, grapes are often left on the vine as long as possible for peak concentration and complexity, but with that comes risk of mildew, rot, and the loss of a crop. It’s no wonder that these bottles are regarded as liquid gold: a labor-intensive and often very tiny harvest without guarantee of a return.