Vinification Flashcards

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1
Q

Primary flavors in wine come from: the grapes, fermentation, or age?

A

Grapes themselves

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2
Q

What sugar does yeast prefer to consume?

A

Glucose

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3
Q

What is the conversion ratio used to estimate potential alcohol in the EU?

A

16.83 grams per litre of sugar in the must yields 1% abv

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4
Q

Yeasts convert roughly what % of sugar into alcohol?

A

90-95%

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5
Q

What is the main acid in grapes, are there others?

A

Tartaric
Yes, Malic & Citric

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6
Q

How do pH and TA differ in the perception of a wine?

A

pH affects texture
TA affects how “sour” a wine will be

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7
Q

What are the three categories of Phenolic compounds?

A

Flavonoids (polyphenols like Anthocyanins and Catechins)
Non-Flavonoids
Tannins

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8
Q

Which method of white wine pressing yields a higher degree of skin contact: destemming before pressing or whole-cluster pressing?

A

Destemming before pressing

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9
Q

In what style of winemaking is whole cluster pressing generally favorable?

A

Sparkling wine production

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10
Q

When does extraction begin in red winemaking?

A

As soon as berries are crushed

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11
Q

Are whole cluster fermentations warmer or cooler than destemmed fermentations?

A

Cooler - stems provide channels for airflow

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12
Q

What style of red winemaking is semi-carbonic?

A

Whole cluster

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13
Q

At what % of alcohol does intracellular fermentation generally stop?

A

2%

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14
Q

What are Pectolytic enzymes?

A

Enzymes that break down pectin in grape skins, used to increase extraction in a short period of time

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15
Q

What are the three methods of rose production ?

A

Direct press
Saignee
Blending

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16
Q

What is cold soaking?

A

Process where red must is held at a cool temperature to inhibit fermentation
Fruit enzymes break down skins to increase color

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17
Q

Are thermoinification and flash detente used in quality winemaking?

A

No

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18
Q

At what point does extraction end?

A

Pressing

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19
Q

What is the press cut?

A

When a winemaker decides when to switch from a light press to heavy press juice

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20
Q

What method of pressing is preferred for quality winemaking: Batch pressing or Continuous pressing?

A

Batch pressing

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21
Q

What is debourbage?

A

Settling of must overnight at a cold temperature then racking off sediment - done post pressing

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22
Q

When is Bentonite clay added to a wine to clarify it? How does it work?

A

After pressing before racking
Natural electrostatic processes (positively charged connects to negatively charged ions in the juice)

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23
Q

How might alcohol be adjusted in the winemaking process?

A

If potential alcohol is too high adding water to the must in tank BEFORE fermentation

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24
Q

During the process of Malolactic fermentation, what does Citric acid turn into?

A

Diacetyl

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25
Q

Does MLF increase or decrease a wines total acidity?

A

Decrease

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26
Q

What is the name of the main wine yeast?

A

Saccharomyces cervisiae

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27
Q

What is the name of the LAB that causes MLF?

A

Oenococcus oeni

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28
Q

Non-saccharomyces yeasts generally die off after what point in the winemaking process?

A

Just after fermentation begins

29
Q

Botrytis is likely to carry what genus of Yeast? What does this yeast produce a lot of?

A

Pichia yeasts
It’s a spoilage yeast that produces a high amount of VA

30
Q

What yeast strain produces a higher proportion of ethyl acetate?

A

Kloeckera apiculata - a cold tolerant yeast

31
Q

Is Brettanomyces bruxellensis an alcohol tolerant yeast variety or not?

A

It is very alcohol tolerant

32
Q

LAB converts glucose into what?

A

Lactic acid

33
Q

What are biogenic amines and what causes them?

A

Off-putting aromas of putrescine and cadaverine
Caused by undesired LAB species

34
Q

What are pyridines and what causes them?

A

Aromas of mousiness, flavors of acrolein (bitter), and causes ropiness
caused by undesired LAB species

35
Q

What is ropiness in wine?

A

It’s a viscous slime that forms from polysaccharides linking together

36
Q

What is the species of Acetic acid bacteria that can live in wine?

A

Acetobacter

37
Q

What causes populations of acetobacter to rise?

A

Exposure to oxygen post fermentation
Can be managed by topping up barrels and also with SO2 during aging

38
Q

Roughly how much C02 is produced in relation to volume of the must ?

A

CO2 is 60x greater than the volume of the must

39
Q

Is fermentation a reductive or oxidative environment?

A

Reductive - CO2 displaces oxygen

40
Q

How many yeast cells per milliliter are generally required for fermentation to begin?

A

Roughly 10 million cells

41
Q

What are the three stages for yeast during fermentation?

A

Lag phase - yeast adapting to environment
Exponential phase - reproduction
Stationary phase - the act of fermentation

42
Q

If nitrogen is too low during a fermentation what aroma can be produced? How does this actually affect the act of fermentation?

A

Hydrogen Sulfide (rotten eggs)
Can lead to a stuck fermentation

43
Q

What are mercaptans? What are they derived from?

A

Bad smelling thiols (skunk, onion, rubber)
Created when hydrogen sulfide is produced and reacts w/ the wine to create other compounds

44
Q

What is the temperature range that yeasts generally are able to operate within?

A

45-95 degrees Fahrenheit

45
Q

What temperature range are yeasts most active in?

A

70-80 degrees Fahrenheit

46
Q

What is the process of Remontage?

A

Pump overs

47
Q

What is the process of Pigeage?

A

Punch downs

48
Q

During Remontage what is the use of the “sprinkler” vs. “fire hose” technique?

A

Sprinkler will be less extractive
Fire hose is much more extraction

49
Q

What is Delestage?

A

Rack and return
Removes the must to another tank w/ skins left behind then pumping the must back over the skins to mix thoroughly

50
Q

Where is Submerged Cap fermentation historically popular?

A

Piemonte

51
Q

Besides Lactic acid, what other compounds are created during MLF?

A

Acetic acid
Acetaldehyde
Diacetyl

52
Q

Where was the technique of microoxygenation popularized?

A

Madrian in the 1990’s

53
Q

What does microoxygenation try and mimic?

A

Aging in a porous vessel like oak

54
Q

What wine fault is risked when microoxygenation is used?

A

Prem-ox

55
Q

What is cliquage?

A

A technique that mimics the oxidative effects of racking with one large hit of O2

56
Q

Are the following forests know for having tight grain, medium grain, or coarse grained oak:
Troncais
Allier
Jupilles
Nevers
Bertranges
Vosges
Limousin
Zemplen Hills (Hungary)

A

Troncais - Tight
Allier -Tight
Jupilles - Tight
Nevers - Medium
Bertranges - medium
Vosges - loose
Limousin - Coarse
Zemplen Hills - tight

57
Q

If wines use 100% new oak how does the price increase per bottle (French and American)

A

French: $3.30-$7.50 / bottle
American: $1.65 + /bottle

58
Q

What is the humidity range where alcohol and water evaporate at the same rate? If lower/higher, what happens to the wine?

A

70%
If lower - alcohol increases as water evaporates w/o the alcohol
If higher - alcohol decreases

59
Q

What is the process of Ouillage? How often is it practiced?

A

Topping up of barrels
Every 2-6 weeks

60
Q

May USDA certified organic wine contain added sulfites?

A

No

61
Q

May USDA certified wine made from organic grapes contain added sulfites?

A

Yes up to 100ppm of SO2

62
Q

When might SO2 be added to a wine?

A

Before fermentation to inhibit bad bacteria or undesirable yeast
During fermentation (stopping it)
After MLF to prevent oxidation
At bottling to inhibit oxidation that naturally happens during bottling

63
Q

What is the French term for racking?

A

Soutirage

64
Q

What is protective racking?

A

An anaerobic way to rack a wine pushing wine from a barrel using inert gasses

65
Q

What is the tool that is used to rack a wine?

A

A racking wand or racking arm

66
Q

How can mercaptans be removed from a final wine?

A

Using copper sulfate - reacts w/ insoluble compounds that fall out of solution

67
Q

What are the legal limits of Copper sulfate use in the US and EU?

A

.5mg/L in the US
1mg/L in the EU

68
Q

What is copper casse?

A

Excess copper in a wine that increases rate of oxidation and can cause haziness or a reddish/brown particulate in white wine