Sweet Winemaking Flashcards
What are the 6 ways to make sweet wines that contain unfermented, residual sugar? (p. 58)
- Stopping the Fermentation
- Adding a Sweetening Component
Concentrating Grape Sugars by: - Noble Rot
- Drying Grapes on the Vine
- Drying Grapes after Picking
- Freezing Grapes on the Vine
How is sweet wine made by Stopping the Fermentation? What are 3 ways of doing this?
(SWA: Stopping the fermentation results in unfermented sugar that creates a sweet wine)
Stopping the Fermentation (p. 58) is traditionally done by Fortification (the addition of grape spirit) while sugar is still present to kill the yeast so no further fermentation is possible. But it radically alters the structural balance of the wine. (Fortified Wines, chs. 43-45). This is used for low-quality styles of Kabinett wine.
For higher quality sweet wines, Stopping the Fermentation can be done by (a) adding a high dose of SO2, or (b) chilling the fermenting wine. Wine must be sterile filtered to remove any remaining yeast. It must be protected from any further yeast contact that could cause fermentation to resume. Chilling or adding SO2 both result in lower alcohol wines (7-9% abv).
What are examples of high-quality Prädikatsweine sweet wines made by Stopping the Fermentation? What is an example of sparkling wine?
Rieslings made into the higher quality and sweeter styles of Kabinett (the most delicate Prädikatsweine) and Spätlese (more body, alcohol, and sweetness than Kabinett) are made by Stopping the Fermentation early (chilling or with SO2) before the yeast has converted all the sugar in the juice to alcohol, producing a better acid/sugar balance.
Asti from Italy is an example of sparkling wine that has higher residual sugar by Stopping the Fermentation using SO2 or chilling.
Note: low-quality Kabinett wines are sweetened by the addition of the Sweetening Component of Süssreserve (unfermented grape juice) to dry wines before bottling.
How is sweet wine made by Adding a Sweetening Component?
Adding a Sweetening Component is the addition of unfermented grape juice, or Süssreserve to make medium-sweet wines, esp. in Germany.
The juice is first filtered before fermentation starts, or by dosing it with SO2. Then süssreserve is added to the dry wine before bottling.
Rectified Concentrated Grape Must (RCGM) can also be used. RCGM can add a little sweetness to high-volume inexpensive wines.
What is an example of a low-end sweet wine made by Adding the Sweetening Component of Süssreserve?
Rieslings made into the sweeter style, but lower quality, Kabinett wines (the most delicate of Prädikatsweine) can be sweetened by the addition of Süssreserve (unfermented grape juice) before bottling.
Note: High-quality Kabinett wines are made by the other method of Stopping the Fermentation early. (p. 109)
How is sweet wine made by Concentrating its Grape Sugars and what are the 4 methods used?
Sweet wines can be made from grapes that are extremely rich in sugar. The grapes are treated in ways that concentrate their sugars as well as concentrate acids and flavors at the same time. The alcoholic fermentation stops naturally when the yeast have converted as much sugar into alcohol as they can. Yeast struggle to survive in very sugary environments so fermentation stops at low levels of alcohol, as low as 7% abv.
The 4 ways are: 1. Noble Rot, 2. Drying Grapes on the Vine, 3. Drying Grapes after Picking, 4. Freezing Grapes on the Vine.
What causes Noble Rot?
Noble Rot is caused by the fungus Botrytis cinerea, the same fungus that causes grey rot but which, under specific conditions, can form noble rot instead.
What are the conditions by which Noble Rot forms?
- The grapes must be fully ripe BEFORE the development of Noble Rot.
- Second, the grapes must be grown in a region that has (a) humid, damp, misty mornings: to allow the rot to develop on the grapes where the fungus punctures the grape skin with microscopic filaments, leaving holes in the skin and (b) sunny, dry afternoons: to slow the development of the rot and cause water to evaporate from the grape, concentrating the grape’s sugars, acids, and flavors.
How are a sweet wine’s aromas and flavors influenced and added to by Noble Rot?
The process of Noble Rot causes the water to evaporate from the grape, concentrating its acids, flavors, and sugars. The fungus also generates its own unique flavors in the grape. Wines made from Noble Rot have distinctive honey, apricot, citrus zest, and dried fruit aromas.
How do grapes with Noble Rot grow on the vine and how are they harvested?
The spread of Noble Rot is never uniform and several pickings by hand may be required. This is an expensive process and requires skilled labor over a prolonged period of time.
Some regions famous for this style of wine, like Sauternes, do not have the ideal conditions appear every year. If conditions are too damp the fungus will develop too rapidly and cause grey rot (also caused by Botrytis), splitting the grapes and encouraging infections.
How is wine made by Noble Rot identified on the wine label?
Although Botrytis causes both noble rot and grey rot, the term Botrytis is often used as a synonym for Noble Rot, and the term ‘botrytised’ is often on sweet wine labels.
What are 5 examples of sweet wine made by concentrating its grape sugars using Noble Rot?
Noble Rot is used to produce most of the very best sweet wines including Sauternes, Tokaji, and Beerenauslesen and Trockenbeerauslesen from Germany (Riesling, pp. 59, 109-110) and Austria, sweets wines of Bordeaux (p. 79)
Trockenbeerauslesen is a classic example of the resulting wine being highly sweet but very low alcohol - 7% abv, because the fermentation stopped so early when the yeast did not survive in such a high sugar concentration environment.
How is sweet wine made by concentrating its grape sugars by Drying Grapes on the Vine? (Late Harvest)
Drying Grapes on the Vine is often referred to as ‘passerillage’ (p. 84) and wines made this way are labeled Late Harvest. Once grapes have reached full sugar ripeness they begin to dehydrate and turn to raisins on the vine, increasing the sugar concentration in the juice. Warm, dry autumns are needed or grey rot will develop. These wines have an overripe character of dried fruit and tropical fruit.
Late Harvest (Passerillage - Drying Grapes on the Vine, free from Botrytis):
High acid Petit Manseng. Jurancon subregion in South West France (p. 84, listed as ‘Other’ in LO2, SW FR).The wine has pronounced apricot and grapefruit aromas, sometimes spicy notes from new oak.
Late Harvest (Passerillage - Drying Grapes on the Vine, free from Botrytis): Chenin Blanc, Savennières subregion of Loire Valley, France. (p. 97). Air circulation in well-exposed vineyards impedes development of noble rot and allows for a Late Harvest Chenin Blanc grapes to be used for full-bodied, complex dry wines with pure fruit flavors.
How is sweet wine made by concentrating its sugars by Drying Grapes after Picking?
Drying Grapes after Picking: After the harvest of healthy grapes, grapes are dried indoors so they dehydrate, concentrating sugars in the juice. Conditions must be dry and warm to avoid grey rot. Care must be taken to remove any rotten grapes so the rot does not spread. (video: Generally, drying indoors is done with grapes on mats or hung from ceiling in rooms with high air circulation (open windows) to keep fruit clean and free of rot. Slow drying period of 3-6 months with fermentation done in following Spring. (Note: p. 123: Passito Method fermentation in winter.)
