Specific Options Wines with Residual Sugar

Question 1

Specific Options Wines with Residual Sugar

What are the three main ways for producing wines with residual sugar?

Answer 1

1. Concentrating the sugar in the grape must
2. Stopping the fermentation before dryness
3. Blending in a sweetening component to the wine

Question 2

Specific Options Wines with Residual Sugar

concentrating the grape must:

Answer 2

The grape must is concentrated by the reduction of the water content in the grape:
- on the vine
- off the vine

• concentration of sugar + acidity + flavour compounds
• lower volume of juice
• fermentation might stop naturally or by chilling and/or adding S02 + filtering yeasts out

Question 3

Specific Options Wines with Residual Sugar

Drying grapes on the Vine:

Answer 3

• Stage four of ripening = grape starts to shrivel: water is lost by grape transpiration and the sugars concentrate.
• Dry autumns are needed for this option to avoid the development of grey rot
• Labelled as ‘Late Harvest’ / Vendanges Tardives (Alsace) / Spätlese (Germany, Austria)

Alternative technique used in Jurançon, south-west France, and is also sometimes used in Australia:
- the cane of the vine is cut or broken off from the vine a short time before harvest: grapes shrivel more quickly
- Reduced hang time = lower risk of grey rot

Question 4

Specific Options Wines with Residual Sugar

Drying grapes off the Vine

Answer 4

• Grapes are picked and then dried
• Can last from days to months
• Bunches of grapes may be laid out to dry in the sun in warm climates, such as southern Italy or Spain or in dried in a temperature- and humidity-controlled room in cooler climates, which gives the ability to speed up drying and avoid the development of grey rot, for example in Valpolicella.
• Called “appassimento method” in italy : Recioto / Vin santo
• Vin de Paille (france)
• Strawine (australia / austria / germany)

Question 5

Specific Options Wines with Residual Sugar

Noble Rot

Answer 5

• Involves the action of the fungus Botrytis cinerea (same fungus that causes grey rot)
• Humid, misty mornings followed by sunny, dry afternoons.
• The fungus punctures the grape skin with microscopic filaments, leaving tiny holes in the skin. The warm sunny afternoons slow the development of the rot and cause water to evaporate from the grape, concentrating its sugars, acids and flavours.
• Also modify some of the aroma compounds: honey, apricot, citrus zest, ginger and dried fruit aromas.
• Used in the production of Beerenauslese, Trockenbeerenauslese, Tokaji, Sauternes
• Edelfaule (Germany)
• Pourriture noble (France)
• The fungus contributes an enzyme (Laccase) that is capable of oxidising a number of components in grape must and wine + relatively resistant to SO2: Chilling, high doses of SO2 and use of inert gases are all options to minimise the oxidation of the must.
• The thick, high-sugar-content must is also difficult to press, clarify and ferment.

Question 6

Specific Options Wines with Residual Sugar

Freezing grapes on the vine

Answer 6

• Healthy grapes to be left to hang on the vine into the late autumn or winter months.
• Water in the grape pulp turns to ice. When the grapes are picked and pressed, this ice remains in the press and the sugar content of the resulting juice is concentrated
• Technique used to produce Eiswein in Germany and Austria and Icewine in Canada.
• Riesling / Vidal / Cabernet Franc: resistant to diseases and extreme cold temperatures
• Often fermented and stored in stainless steel to retain the primary aromas and flavours of the grape variety

Cryoextraction: picking grapes in autumn and freezing it in the winery

Question 7

Specific Options Wines with Residual Sugar

Stopping the fermentation:

Answer 7

The fermentation is halted before the yeast can consume all of the sugar:
- Control over the level of sugar in the final wine.
- Quick.
- Inexpensive.
- Low risk

Methods:
- Chilling to below 10°C and adding a large dose of SO2 + sterile filtration yeast out to avoid re-start fermentation later on
- Fortification with alcohol to kill the yeast to produce a fortified wine.

Question 8

Specific Options Wines with Residual Sugar

Blending:

Answer 8

Adding a sweetening component (easiest way of producing a wine with residual sugar):
- Sugar
- Rectified concentrated grape must (RCGM): neutral, no added flavour
- Unfermented grape juice (Süssreserve): contribute a grape-juice-like character

• The dry wine can be stored until it is ready to be bottled and then the sweetening component blended in (dry wines are less susceptible to spoilage organisms than wines with residual sugar)
• High level of control, enabling high volumes of a consistent product to be made (trials can be made)
• Suited to the production of high volumes of inexpensive wines