Sweet Winemaking

Question 1

How to make wines with residual sugar

Answer 1

1) concentrating the grape must
2) stopping the fermentation before dryness
3) blending in a sweet component

Question 2

How is residual sugar measured?

Answer 2

grams per liter

Question 3

Concentrating the grape must

Answer 3

• used to produce many sweet and lusciously sweet styles that are very good to outstanding
• done by the reduction of water in the grape, concentrating the remaining sugars, acidity, and flavors (quality points)
• the concentration of sugars may be enough to stop fermentation before dryness as yeast struggle in sugary environments (not always)
• sugary grapes are hard to press and can add to cost

Methods:
1) drying grapes on the vine
2) drying grapes off the vine
3) noble rot
4) freezing grapes

Question 4

Drying grapes on the vine

Answer 4

• water is lost by the grape through transpiration, concentrating the sugars
• develops very ripe flavors
• dry autumns are needed for this option to avoid the development of grey rot
• can be done by snipping bunch a short time before harvest, allowing it to hang on the trellising and shrivel more quickly than if still attached / allows high sugar without over ripe aromas (Jurancon, Australia)

Question 5

Drying grapes off the vine

Answer 5

• can last days to months
• bunches may be laid out to dry in the sun in warm climates (S Italy, Spain) or dried in a temperature and humidity controlled room in cooler climates (Valpolicella)
• causes water to evaporate, causing sugars, acids, and flavors to concentrate
• appassimento method used to make Recioto Della Valpolicella and Vin Santo

Question 6

Noble rot

Answer 6

• the fungus Botrytis cinerea
• the grapes must be fully ripe before the development of the rot AND they must have humid misty mornings followed by dry sunny afternoons
• damp conditions allow the fungus to develop on the grapes, puncturing it with microscopic filaments
• warm sunny afternoons cause evaporation
• distinct honey, apricot, citrus zest, ginger, and dried fruit aromas
• sauternes, beerenauslese, trockenbeerenauslese, and Tokaji
• must bc harvested by a skilled person over multiple passes and super low yields = $$$
• not easy to process as they have an enzyme (laccase) that is capable of oxidizing a number of components in wine/must and is resistant to SO2 (chilling, high doeses of SO2, inert gases)
• often aged in oak

Question 7

Freezing grapes on the vine

Answer 7

• requires healthy grapes being left on the vine into late autumn or winter then the frozen grapes are pressed, the ice remains in the press leaving highly concentrated juice
• Eiswein in Germany and Austria / Icewine in Canada must be harvested at -8C/18F or below
• vines must be winter-hardy (Riesling, Vidal, Cabernet Franc)
• often fermented and stored in stainless steel
• freeze and thaw cycles are important of the development of typical icewine character
• difficult to make, risky due to hang-time
• can be created by cryoextraction but isn’t allowed to be labelled eiswein or icewine

Question 8

Stopping fermentation

Answer 8

• winemaker has complete control
• quick and low risk thus generally inexpensive
  1) chill below 10C/50F (then racked off yeast and sterile filtered)
  2) adding a high does of SO2 (then racked off yeast and sterile filtered)
  3) fortification

Question 9

Blending in a sweet component

Answer 9

• wine can be stored dry (thus more stable) until ready to be bottled
• allows for high levels of control
• increases volume
• controlled by local legislation

1) rectified concentrated grape must (RCGM)
2) unfermented grape juice (süssreserve)