Options for Producing Wines with Residual Sugar Flashcards
How does concentrating the grape must work to produce wines with residual sugar?
Concentration of sugars in grape must may be sufficient to stop fermentation before reaching dryness
Yeast struggle in sugary environments, especially when alcohol is present
What methods are available for concentrating grape must in the production of wines with residual sugar
Drying grapes on the vine
Drying grapes off the vine
Development of noble rot
Freezing grapes
Describe drying grapes on the vine
If left on the vine, grapes enter extra ripening stage
Grapes start to shrivel
Water is lost by grape transpiration and sugars concentrate
Flavours develop, giving very ripe flavours
How are wines produced by drying grapes on the vine labelled
Labelled as ‘Late Harvest’
Vendanges Tardives (Alsace)
Spatlese (Germany, Austria)
What is another method of drying grapes while attached to part of the vine?
Can of vine is cut/broken from vine short time before harvest
Grapes shrivel more quickly
Concentrates sugars, acids and flavours
Does not develop extra-ripe flavours
Used in Jurancon (south-West France, Australia)
What are the 2 options for drying grapes off the vine
Grapes dried for days/months - laid out to dry in the sun in warm climates (southern Italy, Spain)
Dried in temperature- and humidity-controlled rooms in cooler climates (Valpolicella)
Referred to as Appassimento
Recioto della Valpolicella and Vin Santo made this way
What effect does drying grapes off the vine have on the grapes?
Causes water to evaporate
Sugars, acids and flavours are more concentrated
Describe Noble Rot
Involves action of fungus Botrytis Cinerea
Grapes must be fully ripe before development of rot
What conditions are required for Noble Rot to develop?
Humid, misty mornings followed by sunny dry afternoons
Damp conditions in morning allow rot to develop on grapes
Warm sunny afternoons slow the development of rot and cause water to evaporate from grape, concentrating sugar, acids and flavours
What are the distinctive aromas of noble rot?
Honey, apricot, citrus zest, ginger, dried fruit aromas
What are examples of sweet wines where noble rot is used
Sauternes
Beerenauslese
Trockenbeerenauslese
Tokaji
What are challenges in harvesting grapes affected by noble rot
Spread of noble rot is not uniform
Several pickings by hand may be needed
Expensive, requires skilled labour over prolonged period of time
Noble rot contributes an enzyme called _______ that is capable of oxidizing a number of components in grape must/wine, and is resistant to SO2
Laccase
How do you minimize the oxidation of must from grapes with noble rot
Chilling
High doses of SO2
Use inert gases
Describe the method of freezing grapes on the vine
Healthy grapes left to hang on vine into late autumn or winter
Water in grape pulp turns to ice
When grapes pressed, ice remains in press
Sugar content of juice is concentrated
What temperature must ice wine grapes be harvested at in Canada
-8C or below
What characteristics do ice wine grape vines need to have to protect from disease and withstand the strain of freeze-thaw cycles
Vines need to be winter hardy
Grapes have resilient skins
What is another method can be used to make sweet wines from frozen grapes
Cryoextraction - freeze grapes in winery
Harvest grapes when ripe
Not permitted for Icewine or Eiswein production
What options are available for stopping fermentation
Chill to below 10C
Add high dose of SO2 to inhibit yeast
Wine racked off sediment and sterile filtered to ensure fermentation does not start again at a later stage
Fortification - addition of alcohol to kill yeast
What are the advantages of using the method of stopping fermentation in producing wines with residual sugar
Winemaker has control over level of sugar in final wine
What is the easiest method for producing a wine with residual sugar? When is sweetening component added?
Adding a sweetening component
Dry wine stored until ready to be bottled and then sweetening component is blended in
What is the benefit of adding a sweetening component to produce wine with residual sugar?
Dry wines less susceptible to spoilage organisms than wines with residual sugar
What are the options for blending in a sweetening component?
Sugar - cane or beet
Rectified concentrated grape must (RCGM)
Unfermented grape juice
