Viniculture Flashcards
What are the 4 prevalent mineral elements in wine?
potassium, calcium, copper, iron
What is lenconostoc used for?
malolactic fermentation
What is the influence of extended skin contact on tannins?
It gives time for short-chain tannins to link up and form long-chain polymers.
How does extended skin contact help enzymes?
There is enough time for the enzymes to disassemble cells in the skins, which allows everything the skins have in the way of color, flavor and fragrance to enter the wine.
What is a good temperature for fermenting red wines?
80-85 degrees F
Rotundifolia is usually deficient in what?
Nitrogen
What is a slow-eating yeast often used for Pinot Noir?
Assmanhausen
What is Flor Sherry yeast?
Saccharomyces fermentati - AKA UC Davis 519
The culture needed to produce flor or fino-type sherries in hot, dry regions.
What is Epernay 2 yeast?
Saccharomyces cerevisiae
A slow-fermenting, general purpose strain. Used for reds, whites and sparkling.
What is California Champagne yeast?
Saccharomyces bayanus - UC Davis 505
Slow to moderately vigorous, with extremely rapid, compact precipitation of spent yeast lees. Facilitates riddling of bottle-fermented sparkling wine.
What are the characteristics of Pasteur Champagne yeast?
Developed by Pasteur Institute and numbered UC Davis 595. Moderately vigorous with high SO2 and alcohol tolerance. Used for all wine types but especially for sparkling wines and stuck fermentations.
What is Montrachet 522?
A popular strain of Saccharomyces cerevisiae.
When is the yeast added?
About a day after the sulfite is added.
Reds with a pH less than 3.3 tend to resist what?
malolactic fermentation
Where is it possible to see high TA and high pH?
Washington State
What are two safe ways to reduce acid?
- Inoculate the must with malolactic bacteria toward the end of the primary fermentation.
- Cold stabilize the wine
TA minimum for reds is what?
Whites?
- 55
0. 65
If the pH rises, how could sulfite amount be changed?
raised
Too much SO2 can do what to a must?
Destroy tannins and flavor constituents
The FDA allows how much sulfite in wine?
350 ppm
What does the Walthari method use instead of sulfite?
Carbon Dioxide
What do winemakers use to kill off or stun into stupefaction all yeasts and microorganisms in the must as soon as it’s pressed?
potassium metabisulfite
Many yeasts die off at what percent alcohol concentration?
4-6%
Why do white grape varieties give a greater yield of juice after 16 hours of skin contact?
Due to the softening and enzymatic breakdown of cells in skins and pulp.
What do fruit flies carry?
Acetobacter bacteria
Why is it a bad idea to cool grapes by hosing them with cold water?
It will immediately reduce the quality of the grapes by producing conditions for bad mold spores and off-flavored yeasts to multiply.
When should grapes be crushed?
Immediately after picking.
What is “topping up”?
Adding a second and similar wine to a vessel to fill it up, when the wine you have doesn’t reach the top.
What is “sticking”?
A stoppage of fermentation before sugar is entirely converted to alcohol, usually due to yeast dying off from lack of nutrients or to chilling.
What is a hydrometer?
An instrument for measuring the specific gravity of liquid.
What is enology?
The science of winemaking.
What is an airlock?
A device that allows gas to escape from a vessel containing wine, but allows no air to enter.
What is bousinage?
Toasting a wooden stave.
What is cintrage?
shaping a wooden stave
What is chauffage?
warming a wooden stave
How is American oak usually dried?
In a kiln
How is French oak usually dried?
In air
Which oak is less likely to be sawed?
French
What causes wider grain in oak?
quicker growth
What is the usual American oak species?
Quercus alba
French oak comes from what trees?
quercus robur and quercus petraea trees
What is micro-oxygenation?
An aeration technique in which small amounts of oxygen are allowed to enter a stainless steel tank during either fermentation or maturation of wine.
In what ways does oak contribute to flavor?
Lactones and phenolic aldehydes
What is saignee?
Bleeding juice from a red wine fermentation in order to produce a rosé.
What are the two basic methods of rosé winemaking?
Blending, and limited skin maceration.
Why are off-dry and sweet white wines often filtered?
The sugar content can lead to unexpected refermentation, in the bottle.
What is sussreserve?
Sterilized fresh grape juice added to wine after it ferments to dryness.
At what temperature does cold stabilization happen?
25 degrees F
What is débourbage?
Allowing the juice to settle after pressing.
Extended skin contact in white wine fermentation lasts how long?
A few hours
Filtration is accomplished through the use of what?
Pads, or a membrane with microscopic openings.
What are common fining agents?
Bentonite, casein, isinglass, gelatin, egg white
What is collage?
fining a wine
What is soutirage?
racking
What is élevage?
The maturation period of wine in barrels.
The traditional basket press relies on what to press the pomace?
vertical pressure
What is vin de presse?
Wine left after vin de goutte that is pressed with pomace to yield coarser, tannic wine.
What is vin de goutte?
Free-run wine
What is common for fuller-bodied reds, after fermentation?
extended maceration
What is délestage?
A technique that allows the winemaker to fully drain the fermentation vessel, by racking the wine into a separate vessel.
What is remontage?
Pumping the fermenting wine over the top of the cap.
What is pigeage?
Punching down the cap.
What happens to the chapeau without intervention?
It will dry out, solidify, and prevent extraction.
What is a chapeau?
The cap of pomace during red wine fermentation
When and where was cold soak developed?
Burgundy in the 1970s
What is an addition to cold soak maceration?
SO2 - Sulfur Dioxide
What was the traditional reason for a pre-fermentation maceration in red wine production?
To wait for ambient yeasts to ignite fermentation
Damaged or unripe stems may cause what?
Undesirable green flavors in the wine
Why might stems be retained for fermentation?
For spicy aromatic complexity and structure.
What does whole berry fermentation encourage?
carbonic maceration
What 2 grapes commonly go through whole berry fermentation?
Pinot Noir, Syrah
What’s MOG?
material other than grapes
Ending carbonic maceration, the berry ceases activity in the presence of enough _____.
ethanol
Carbonic maceration occurs without what two factors?
oxygen and yeasts
What happens in the grape during carbonic maceration?
A berry will release enzymes to transform its own sugar into ethanol and carbon dioxide.
What compound is commonly a byproduct of malolactic fermentation?
diacetyl
What are two likely places to find lactic acid bacteria?
Via inoculation, and alongside yeasts or grape skins.
What are the two results of malolactic fermentation?
lactic acid and carbon dioxide
What is acidification?
The addition of acid to must or to a finished wine.
The EU allows reverse osmosis alcohol adjustment by how much?
When did this start?
2%
2009
What does reverse osmosis do?
Separates the wine into two constituent parts, permeate and retentate. The permeate (water & ethanol) is distilled to a proper level before being recombined with the retentate (aromatic compounds).
How long does it take for a wine to ferment dry?
1 week - a bit more than a month
What is commonly used to eliminate ambient yeast in must?
sulfur dioxide
Cultured yeasts tend to be able to work in higher levels of ______ than ambient yeasts.
alcohol
What is batonnage?
lees stirring
What is the most obvious weakness in barrel fermentation?
The lack of temperature control.
Fermentations over _____ degrees F run the risk of volatized flavor compounds and stuck fermentations.
95 degrees F
What is the workable temperature range of yeast?
50 degrees - 110 degrees F
Sulfides refers to what?
Hydrogen Sulfide (H2S), Mercaptans, and other foul-smelling compounds produced under reductive conditions.
Sulfites refers to what?
Sulfur dioxide (SO2)
What commonly creates the smell of rotten eggs?
Hydrogen Sulfide (H2S)’s creation in must through existence of low levels of nitrogen.
What creates volatile acidity?
Excessive acetic acid that has been produced by the activity of acetobacter.
When acetic acid reacts with alcohol, what does it create?
ethyl acetate
A small amount of acetalhyde is converted to what?
acetic acid
Acetalhyde is regarded as a sign of what in finished wines?
oxidation
Why is sulfur dioxide added to the fermenting must of the juice beforehand?
To prevent oxidation and bacterial contamination, and to ensure rapid fermentation.
What are some usual volatile compounds produced in alcoholic fermentation?
Acetaldehydes, ethyl acetate, fusel oils, sulfur dioxide.
What is the process of alcoholic fermentation?
The metabolism of yeast cells converts sugar in grape must into ethyl alcohol (ethanol) and carbon dioxide (CO2).
