Residual sugar is the sugar content left in the wine after bottling. Dry wine always has lower sugar content and sweet wine has higher sugar content.
If the alcoholic fermentation convert all the sugar in the grape juice into alcohol, the wine has little sugar and that is the dry style. For the still dry wines, the residual sugar level is less than 4 grams per liter.
If the alcoholic fermentation stops before all the sugar in the grape juice is converted into alcohol, there are some residual sugar in the wine. A little sweet can be tasted on the palate, but it is not clear. The wine could be off-dry or medium dry style. The residual sugar level of still wines ranges from 4 to 12 grams per liter.
If you can taste the sweetness clearly on the palate, but it is not luscious sweet, it should be medium-sweet at least. The sugar level of still wines ranges from 12 to 45 grams per liter.
If you can taste the luscious sweetness on the palate, it should be sweet wine. The sweet wine has a residual sugar level of more than 45 grams per liter. Some most luscious sweet wine has more than 200 grams per liter residual sugar, even as high as 900 grams per liter.
How to make sweet wines?
What is the most important factor that has to be considered for sweet wine?
Acidity, absolutely it is acidity level. Because the high sweetness level need high acidity level to balance, otherwise it will taste too sweet and lose its freshness.
In some high quality sweet wine, people always choose natural high acidity grape variety, such as Riesling and Chenin Blanc. But some winemaker choose to blend.
In Sauternes, for example, wineries choose Sémillon to make botrytised sweet wine, because of its thin skin susceptible to botrytis cinerea. Sémillon has a full body and accumulates sugar easily, but lacks of acidity. So winemakers choose to blend high acidity Sauvignon Blanc into the wine, to develop higher acidity level to balance the high sweetness level.
Riesling has a natural high acidity even in a warmer climate condition. So it has the potential to make sweet wine. In Alsace and Germany, wineries can use Riesling to produce medium-sweet to sweet wines. Several methods can be used, such as late harvest, botrytis, Eiswein.
Chenin Blanc is another grape variety fit for sweet winemaking. It is widely grown in Anjou-Saumur in Loire Valley, and is used to make late harvest or botrytised sweet wines from off-dry to sweet style
Different label terms for residual sugar level
- Dry, residual sugar is less than 4 grams per liter.
- Medium-dry, residual sugar is from 4 to 12 grams per liter.
- Medium-Sweet, residual sugar is from 12 to 45 grams per liter.
- Sweet, residual sugar is over 45 grams per liter.
Most famous sweet wines
- Vendanges Tardive is the late harvest wine which is produced in Alsace, in France.
- Spätlese is the late harvest wine which is produced in Germany.
- Selection de Grains Nobles is the noble rot sweet wine produced in Alsace.
- Beerenauslese is the noble rot sweet wine produced in Germany.
- Trockenbeerenauslese is the noble rot sweet wine produced in Germany, and the residual sugar level is higher than Beerenauslese.
- Tokaji Aszu Late Harvest is made from the noble rot grapes.
- Tokaji Aszu 5p and 6p are made from the noble rot grapes, and the the residual sugar level is higher than Tokaji Aszu Late Harvest.
- Tokaji Escenzia is made from the noble rot grapes, and is the highest residual sugar level in Tokaji sweet wines. Tokaji Sweet wines are produced in Hungary.
- Eiswein/Icewine is a sweet wine which is made from the natural frozen grapes. The most famous Icewine are produced in Germany, Austria and Canada.
- Sauternes and Barsac are two most famous botrytis sweet wine producing AOCs in Bordeaux, made from the Sauvignon Blanc and Semillon grapes.
- Port is a fortified sweet wine. the high alcoholic level spirits are added in the fermentation process, so the fermentation process is finished before all the sugar are converted into alcohol.
- Sherry can be sweet style by adding sweet component after dry style sherry is made or made from just sun-dried grapes, such as PX Sherry. Sherry is made in Spain.
- VDN is a fortified sweet wine, made from Muscat or Grenache grapes and is fortified in the fermentation process. They are produced in Southern Rhone Valley and Languedoc-Roussillon.
- Rutherglen can be a fortified sweet wine, made from Muscat grapes, and which is produced in New South Wales in Australia.
- Moscato d’Asti DOCG is a sweet sparkling wine produced in Piemonte in Italy. It is made from Muscat grapes and stops fermentation early by decreasing the temperature of grape juice and filtering the yeast.