See more on Ernst Loosen: The Doctor Made a House Call - A Tasting with Ernst Loosen, Weingut Dr. Loosen, at MacArthur Beverages in Washington DC, USA
On my trip last year to the Soave region in Italy, I was introduced to Reciotto di Soave. This is a sweet wine. It triggered in me the desire to do a bit of research with a view of finding out how the sugar gets into sweet wines.
Normally, Wine is Dry
Normally, wine is dry: the sugar, naturally present in grape juice, is transformed into alcohol and carbon dioxide by the action of yeasts during fermentation - the sugar content of the must declines and eventually disappears, while the alcohol content builds up. Fermentation, however, stops naturally, when the alcohol has reached a certain level – around 15%. Thus, any sugar that is still in the must at that point of fermentation remains in the finished wine and makes the wine sweet. But this happens only under very special circumstances. Even in hot climate countries, the sugar that is in the grapes at harvest disappears completely as a result of fermentation. Thus, normally, wine is dry. But …. there are many wines that are not dry. How do wine producers do this?
For more, see: German Wine Basics: Sugar in the Grape - Alcohol and Sweetness in the Wine
Making Wine Sweet
There are a number of different approaches:
Grow grapes so sweet that they naturally have sugar to spare for both sweetness and alcohol?
This is an approach that exists as far as I know only in theory. I am not aware of any such wine. Often, the German Spaetlese and Auslese wines are mentioned in this category. But this is wrong. Germany is a cool climate country and German wine makers have always been struggling to get fully ripe grapes, although less so in recent years as a result of climate change. Of course, there are these world renowned fruity-sweet German Spaetlese and Auslese wines. But they are sweet, because of either arresting the fermentation or adding sweet reserve (see below). If you just leave it to Mother nature in the wine cellar, these wines would become bone-dry.
Add sugar before fermentation (Chaptalization)?
Chaptalization – adding sugar to the grape juice before fermentation - is a common practice in many countries, invented in France. However, sugar is regularly added to boost the alcohol levels of flabby, unripe wines rather than for sweetness.
The EU wine law limits the amount of additional alcohol that can be achieved through this cellar technique to 3.5% by volume and 2.5% by volume, depending on the wine region.
Forced interuption of the fermentation with temperature control or similar methods
This is a very popular technique in Germany, done through a skillful manipulation of the fermentation process, such as dropping the temperature during fermentation and/or filtering out the sugar-consuming yeast. The winemaker needs to follow closely the fermentation process and must make sure that it comes to a stop at the desired level of sweetness.This is the way, the delicious low alcohol, fruity-sweet German Spaetlese and Auslese wines are produced.
Add sweet reserve (sterilized juice) after fermentation
This is a German technique in which sterilized grape juice is added to the wine after fermentation. In Germany, the final wine can contain no more than 15% sterilized juice by volume. This approach is less popular today than it was years ago; most German fruity-sweet wines are made by stopping the fermentation.
Often, the two approaches - arresting the fermentation and adding sweet reserve - are used in combination: You stop the fermentation at about the desired level of sweetness and then you fine-tune the level of sweetness by adding sweet reserve.
Sweet Sherry is also made by adding sweet reserve (see below).
Add alcohol before or during fermentation (fortification)
By adding alcohol, you drive up the alcohol level in the must so that the fermentation stops naturally, while not all sugar that was in the grapes is converted into alcohol. The main fortified wines are Port, Sherry, Madeira and vins doux naturels.
While Port wine is made sweet by adding alcohol to the fermenting must so the fermentation stops and the sugar of the grapes remains in the wine, Sherry, on the other hand, is made by letting the fermentation go its full way so that a dry wine emerges. Then, alcohol is added to boost the alcohol level. If the winemaker stops there, you get a dry Sherry. If he also adds sterilized juice, you get a sweet Sherry. Thus, Sherry can be sweet or dry, while Port is always sweet.
See: Meeting Rupert Symington from the Symington Family - One of the Oldest Families of Port Producers
Madeira is a fortified Portuguese wine made in the Madeira Islands. Madeira is noted for its unique winemaking process which involves heating the wine up to temperatures as high as 60 °C (140 °F) for an extended period of time. Furthermore, Madeira is deliberately exposed to air, causing it to oxidize. By contrast, sweet Sherry is not fortified.
The production of vins doux naturels was perfected by Arnaud de Villeneuve at the University of Montpellier in the 13th century and they are now quite common in the Languedoc-Roussillon of southwest France (Muscat de Rivesaltes, Muscat de Frontignan, Banyuls, etc.)
Remove water - in frosty climates - by freezing out some of the water to make ice wine
Most wine laws require temperatures below at most −7 °C (19 °F) before the grapes for ice wine can be picked. At such temperatures, some of the water in the grapes freezes out, but the sugars and other solids remain dissolved in the remaining juice. If the grapes are pressed whilst frozen, a very concentrated must can result, which needs special yeast and a long time to ferment. The most famous ice wines are German Eiswein and Canadian ice wine.
Alternatively, the freezing can take place in the wine cellar (cryoextraction). This is an approach, which kind of simulates the frost in the vineyard in the wine cellar. It was developed by the French. Instead of waiting for Mother Nature to produce frosty temperatures in the vineyard, the winemaker subjects the grapes to frosty temperatures in the cellar and presses them while frozen.
For more, see: Eiswein in Germany and Ice Wine in Canada
Remove water - in damp temperate climates - by using a fungal infection (Botrytis cinerea, noble rot)
Botrytis cinerea is the key to the success of many of the world’s most famous noble sweet wines. Also known as noble rot, Botrytis cinerea is a fungus that under the right conditions attacks already-ripe grapes, shriveling them, concentrating the sweetness and acidity. The grapes end up looking disgusting but they make profound sweet white wines.
The sugar content of the grape is exceptionally high at the time of the harvest and Mother Nature is unable to ferment all the sugar. Thus, natural sugar remains in the wine and makes the wine sweet.
Noble sweet wines made on the basis of noble rot are produced in a number of countries. The most famous ones are the Sauternes in France, the Beerenauslese and Trockenbeerenauslese in Germany and in Austria, the Austria Ausbruch and the Tokaji from Hungary. No doubt, the first noble rot wines were created by accident - both the Hungarians and the Germans have similar stories of how the harvest was delayed for some reason, but the over-ripe grapes were vinified anyway and then the resulting wine found to be delicious.
For more on Hungarian noble-sweet wines, see: Tokaji: Depressing and Encouraging News from Hungary
Remove water by air drying (in hotter climates) the grapes (raisin wine)
Northern Italy is home to a number of raisin wines, where the grapes are dried on straw, on racks, or hung from the rafters. Across the Alps, the French make straw wine (vin de paille). The Austrians also make straw wine while it is illegal in Germany.
For more, see: Wining and Blogging in the Soave Region, Italy
schiller-wine - Related Postings
Wining and Blogging in the Soave Region, Italy
Eiswein in Germany and Ice Wine in Canada
Tokaji: Depressing and Encouraging News from Hungary
Meeting Rupert Symington from the Symington Family - One of the Oldest Families of Port Producers
German Spaetlese Wines Can Come in Different Versions. I Have Counted Five.
1.International Riesling Symposium
Impressions from the Riesling and Co World Tour 2010 in New York
When Americans Drink German Wine - What They Choose
German Wine Basics: Sugar in the Grape - Alcohol and Sweetness in the Wine
JJ Pruem Goes Supermarket: Meeting Katharina Pruem and Tasting the Incredible JJ Pruem Wines at Wegmans
Visiting Wilhelm Weil at his Weingut Robert Weil in Kiedrich, Germany
Tasting with Wilhelm Weil the 2010 Weingut Weil Wines in Kiedrich, Germany
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