Stage 4
Other Styles of Wine
Sweet Wines
There are a number of ways to produce a sweet wine:
- Interrupted Fermentation - In this method the fermentation is stopped before all the sugar has been turned to alcohol. This can be done by filtering out the yeast or by using sulphur to kill the yeasts. It can also be done by the addition of alcohol to the fermenting must before all the sugar has been turned into alcohol thus leaving an alcoholic sweet wine. Examples include Port, and Vin Doux Naturels such as Muscat de Beaumes de Venise AC.
- Noble Rot - grapes are picked when affected by Noble Rot which shrivels the grapes and concentrates the sugars, acids and flavours. The wine is fermented and yeasts die when the alcohol level reached approximately 15%. As the pa level was much higher than this the resulting wine has a great deal of residual sugar remaining.
- Dried Grapes - Passito, Recioto, Vin Santo - Drying grapes concentrates the sugars, acids and flavours by evaporating the water from the grape. The concentration of sugars is very high and therefore when the alcohol level reaches 15% during fermentation the yeasts die and the wine remains sweet and alcoholic.
- Ice Wine and Eiswein - the grapes are picked and pressed when frozen and the ice particles removed. This leaves concentrated sugars, acids and flavours. During fermentation the yeast dies when the alcohol level reaches 15% and because the pa level was higher than this the wine is sweet.
- Addition of a sweet component - the most common addition is Sussreserve, which is, unfermented grape juice.
Sweet Wines of Bordeaux
Sauternes is in Bordeaux and is surrounded by the Graves district. This appellation is reserved for sweet wines only made from a blend of Semillon, Sauvignon Blanc and Muscadelle. The wine is sweet and is made from grapes affected by Noble Rot. Semillon is especially susceptible to noble rot and accounts for 80% of a typical blend. Sauvignon Blanc provides the high acidity and freshness that balances the richness of Semillon. Muscadelle contributes aromas but it can be difficult to grow.
Sauternes is close to the river Garonne and its tributary the Ciron. In the autumn the cool waters of the Ciron flow into the warmer waters of the Garonne and evening mists develop which envelope the vineyards. In the morning the sun burns the mists away. This moist atmosphere encourages the growth of fungus called Noble Rot, which attacks the grapes causing them to shrivel and rot. The overall effect of Botrytis infection is to increase the concentration of acid and sugar in the grapes and it also alters the aroma and flavour of the finished wine.
The harvest is protracted as the picking may be interrupted by bad weather or the fact that much of the vineyard has not yet been affected by noble rot. If this is he case the pickers have to visit the vineyard on a number of occasions only picking the affected grapes each time.
The fermentation can be long and drawn out because of the high sugar content which makes it a tough job for the yeast. The sugar level is so high that the potential alcohol level is very high indeed however, the yeast will die once the alcohol level has reached around 14% abv. This means that there will still be a lot of sugar left in the wine, which is why the wine is sweet.
Key Regional Grape Varieties
- Semillon
- Sauvignon Blanc
- Muscadelle
German Sweet Wines
German Sweet Wines are categorized based on ripeness levels:
- Auslese wines are late harvested and are usually sweet
- Beerenauslese will be made with noble rotted grapes
- Trockenbeerenauslese are the sweetest of all and made with shrivelled botrytis affected grapes
Producers in Germany often ferment the wine to dryness and then add Sussreserve, which is unfermented grape juice. This approach will produce a sweet wine but it will be lacking in a fruity dimension.
Tokaji is a sweet wine from Hungary. It is made by vinifying a dry wine from grapes not affected by Noble rot and adding to them a paste made from Noble Rotted grapes. Varying levels of sweetness are available described by how many puttonyos of the sweet paste has been added. A puttonyos is a measuring scoop. Tokaji Aszu containing 3 to 6 puttonyos and Tokaji Aszu Essencia will contain 7/8 puttonyos.
Ice Wine and Eiswein
Ice Wine is made in Canada using grapes such as Riesling and the French hybrid Vidal. The grapes are picked and pressed whilst frozen and the ice crystals removed. This removal of water concentrates the sugars and acids. The wine is fermented until the yeast dies when the alcohol level reaches around 15% and the resulting wine has a high residual sugar content which makes it very sweet. Still and sparkling versions are available and it is usually sold in 37.5 bottles and costs between £40 and £50. Eisewein from Germany and Austria is slightly less sweet than its Canadian counterpart.