Vinification Flashcards
Why is SO2 generally added to fermenting must or juice beforehand?
To prevent oxidation and bacterial contamination and to ensure rapid fermentation.
How is volatile acidity (ethyl acetate) created in wine? (Chemical reaction)
small amounts of acetaldehyde present naturally in finished wine is converted to acetic acid, which in turn reacts with alcohol to produce ethyl acetate
What happens when excessive volatile acidity in the wine has led to the wine becoming faulty?
excessive acetic acid has been produced by the activity of acetobacter, the group of bacteria responsible for turning wine to vinegar in the presence of oxygen.
What happens when the amount of nitrogen present in the fermenting must is deficient?
Because yeast require nitrogen to work, low levels of nitrogen in the must leads to the formation of hydrogen sulfide (H2S), a highly volatile compound reminiscent of rotten eggs.
What compounds are produced under reductive conditions in a fermenting must?
sulfides including H2S, mercaptans and other foul-smelling compounds
Below what temperature will most yeasts cease to act? Above what temperature will most die?
Below 50F most yeasts will cease to work
Above 105F yeasts will die.
If whole berries are used in the fermentation, what will occur? What grapes is this method commonly used on?
Will cause partial carbonic maceration.
Pinot Noir and Syrah are common grapes that are fermented in this manner
What does whole-cluster fermentation promote?
Better movement of juice and air through the cap.
What does cold soak aim to achieve? How is it promoted? How long does it typically last? Where was it pioneered and when? What is the most common grape to employ this technique on?
Aims to achieve the extraction of color and tannin prior to fermentation.
It is promoted by allowing must treated with SO2 to macerate under temperatures too cold for yeast to start fermenting, but not cold enough to prevent extraction of color and tannin.
Typically lasts for nearly a week before fermentation
Pioneered in Burgundy in the 1970s
Pinot Noir is the most common grape that this technique is used on.
5-10 degrees C or 40-50 degrees F
When does maceration occur-before, during, or after fermentation?
Can occur at each period.
Cold soak maceration (pre fermentation)
Normal maceration (during)
post-fermentation for tannic styles like Nebbiolo which can last up to a month following the end of fermentation.
What does soutirage refer to? What does it provide for the wine?
soutirage refers to the racking or movement of wine from one vessel to another, providing aeration and clarification as the wine is removed from its lees, or sediment.
What is the French term for fining?
Collage
What are 5 agents commonly used for collage (fining)?
bentonite
casein (a milk protein)
isinglass (material obtained from sturgeon bladders)
gelatin
egg white
What are the two most common species of French oak used?
- Quercus robur
- Quercus petraea
What is the main American oak species?
Quercus Alba
What are the French terms for warming, shaping, and toasting oak staves respectively?
chauffage (warming)
cintrage (shaping)
bousinage (toasting)
What is Prep 500?
Description: Manure from a lactating cow placed inside a cowhorn and buried during winter.
Use: Stimulates soil microbial life and encourage root growth.
Application Method: Applied in spring and fall, preferably within half an hour of sunset, on recently worked soil.
What is Prep 501?
Description: Paste of silica (powdered quartz) and water placed inside a cowhorn and buried during summer.
Use: Encourages photosynthesis and ripening.
Application Method: Applied in late spring or early summer, preferably at sunrise and never on young vines. Must be applied after Prep 500.
What is Prep 508?
Description: Horsetail plant boiled into a tea.
Use: Fights fungal infections.
Application Method: Can be combined with fungicide and sprayed on the vine or fermented first and sprayed on the soil during the waxing moon. Must be applied after Preps 500 and 501.
Name 3 teinturier grapes
- pontac
- alicante bouchet
- colorino
- chambourcin
De-stemming and cold soaking were innovations introduced by which winemaker?
Henri Jayer
How does humidity (below 70%) effect maturation?
- low humidity causes water to evaporate faster than alcohol
- unfavorably concentrates wine
- raises alcohol content
How long does post fermentation maceration last?
A few days to a few weeks
Describe the contact press method of tartrate stabilization
- wine cooled to 32 degrees F
- potassium bitartrate crystals added to speed precipitation
- filtered after 1 - 2 hours
