Winemaking Flashcards
Gentle pressing of white grape clusters does what?
Avoid violent ripping and tearing
= Cleaner must with less gross particulate matter
What sort of press mostly used for white wine?
Pneumatic or bladder press
Sulfites naturally produced in fermentation to what level?
10-15 ppm
What does adding sulfur during winemaking do?
Prevent browning
Prevent microbial spoilage
Offsets oxidative process
What accounts for use of less sulfur these days than before?
Improved winery hygiene
What is débourbage?
Juice settling after pressing
French term for juice settling
Débourbage
What does juice settling (débourbage) do?
Allows heavier particles to settle out of the solution
Eliminates bitter compounds (eg phenolics)
White fermentation in temperature controlled tank usually at what temperature?
18-20°
What is batonage?
Lee’s stirring
Barrel fermented white (eg Pessac Léognan) usually accompanied by what two steps?
Sur lie ageing
Batonnage
Whites usually filtered with what?
Bentonite
When are whites usually bottled?
Spring or early summer
Why does batonnage give a creamier mouth feel?
Incorporates manoproteins into the wine
General rule, what % of red wine is bled from the tank to make rosé or Clairet?
20-25%
Malolactic in rosé or Clairet?
Usually avoided to maintain freshness
Botrytis spores germinate in what conditions?
After a rain while the canopy is wet and/or
When ambient humidity is 90% and temperatures moderate (15-20°)
Botrytis reduces grape sugar content by what?
1/3
Botrytis leads to overall increase in total extract. True or false?
True.
Reduces sugar by 1/3
Reduces tartaric acid by 5/6
Reduces malic acid by 1/3
Water content reduced by half
Diminished proportion of liquids to solids = more extract
Botrytis transforms sugars and acids into which compounds? (4)
Glycerol
Acetic acid
Gluconic acid
Botryticine (an antibiotic)
Ripe Sémillon should hint of?
Apricots
Ripe Sauvignon Blanc should hint of? (2)
Grapefruit
Pineapple
Ripe Muscadelle should hint of?
Grape
How long can pressing last in botrytis sweet winemaking?
5-6 hours
What is cryo extraction?
When grapes have absorbed too much water from autumn rains..
Chill the grapes to -5° -8° for 20 hours
Then process
Excess water locked up in ice pellets, only concentrated sugar syrup is extracted during pressing
Has fallen out of favour
One vine of botrytised grapes yields how many glasses of wine?
1-3
Biggest microbial threat in sweet winemaking?
Acetobacter
Débourbage (Juice settling) in sweet winemaking?
Yes, but only eliminates the gross particulate matter
Finer particles remain in solution due to viscosity of the juice
Sur lie ageing and batonnage in sweet winemaking?
Yes, to achieve greater complexity
Maturation of sweet wine eg Sauternes?
Blending takes place after first racking
Blended wine then matured in oak for 12-24 months
Barrels topped up weekly
Racking every 3 months
When did Louis Pasteur discover yeast?
1863
What can green stems impart on a wine?
Bitter astringency
What can brown stems impart on a wine?
A touch of spice
19th century red Bordeaux Vs today
Lighter colour
Lower alcohol (10% Vs 13%)
Less tannic
Why is concrete a good insulator?
Slow to hear but once hot retains a gentle warmth post fermentation that enables spontaneous MLF
(Stainless steel tanks must be heated for MLF to occur)
Chaptalisation legal or illegal?
Legal
NB sugar levels within the berry at harvest rising due to global warming
Red wine fermentation temperature range
27-28°
How long does red wine fermentation usually take?
1 week
Followed by maceration (cuvaison) of 2-4 weeks
Red wine racking how often?
Every 3-4 months
Removes particulates that have settled out of solution
Red wines fined with what? (3)
Egg whites
Bentonite (clay)
Gelatin
What does rain at harvest do?
Dilutes all the flavour compounds that have amassed in the berry during the growing season
The grapevine root absorbs the rainwater and translocates to the grape
Old school way to eliminate excess water in juice after harvest rain?
Bleed the tank (saignée)
Pull 15% of juice out of vat before ferment increases skin to juice ratio = more concentrated red wine
Juice fermented to dry rosé
Problem is that too much sugar and aromatics end up in the rosé, not the red wine
Criticism of reverse osmosis and entropy Evaporation?
Unbalance the wine by raising tannin, acid and alcohol levels - arguably to a point of unbalance
What do reverse osmosis machines do?
Membrane filtration at high pressure
Remove 4-10% of water content
What does entropy evaporator do?
Subjects grape must to a vacuum at moderate temperature (20-25°) to remove 15% approx of water
Typically only a portion of the must is processed
What do spinning Cone Columns do?
Remove excess alcohol
Vertical column of 40 cones (some spin and some stay fixed)
Wine passed through and spun into thin film by spinning cones
Collected on stationary cones
Lighter smaller molecules spin off as vapour, condensed and saved
First it’s aromatics, then alcohol
Aromatics blended back in
Alcohol blended back in at winemakers discretion
What is cross Flow filtration?
Removes alcohol
Continuous stream of wine through semi permeable membrane designed to block passage of certain components, eg alcohol
