Vinification

Question 1

how is potential alcohol measured?

Answer 1

every 16.83 g/l of sugar in the must = 1% potential alcohol

but actual conversion ratio depends on efficiency of the yeast and typically ranges from 16.5 to 17.5- and between 5-10% of the sugar is not not able to be converted to alcohol

Question 2

1 KMW is equivalent to approximately how many degrees Öechsle?

Answer 2

5

Question 3

What does the Öechsle scale measure?

Answer 3

On the Oechsle scale, one degree Oechsle (°Oe) corresponds to one gram of the difference between the mass of one litre of must at 20 °C and 1 kg (the mass of 1 litre of water)

1 L of must weighing 1036 grams = 36 degrees Oechsle

Question 4

What does Baume measure?

Answer 4

a specific gravity measurement. compares must weight to water with dissolved salt

juice at 14 degrees Baumé is likely to have a final alcohol concentration of about 14%. Baumé is converted to Brix by multiplying by a factor of 1.8.

Question 5

What does Brix measure?

Answer 5

a speciic gravity measurement. compares must weight to water with dissolved sucralose. measures all dissolved solids, so it slightly overstates sugar proportion

1 degree Brix is equivalent to 1% sucrose by weigh

Question 6

TA

Answer 6

titratable acid - determines perception of sourness—wine with a high titratable acidity (TA) tastes more sour.

during ripening, TA goes down, and pH goes up

Question 7

wine pH

Answer 7

most wine is 3-4 pH
water is 7

during ripening, TA goes down, and pH goes up

Question 8

catechins

Answer 8

small polyphenols that are extracted mostly from seeds and stems (though also from skins) and are largely responsible for bitterness in wine. While the concentration of catechin in wine is low, they are significant in wine as they are a major constituent of tannin.

Question 9

anthocyanins and acid

Answer 9

Anthocyanin’s color is pH dependent, appearing redder at low pH (more acidic) and more purple at higher pH (less acidic)

Question 10

when are the main phenolics extracted?

Answer 10

Anthocyanins extract rapidly at the beginning of fermentation. Tannins and catechins are more soluble in alcohol than water, so their rate of extraction is faster toward the end of fermentation

Question 11

primary acid that occurs naturally in grapes?

Answer 11

Tartaric acid

Question 12

degrees brix at harvest?

Answer 12

Question 13

physiological ripeness

Answer 13

maturity of color, tannins, and flavors

Question 14

physical signs it’s time to harvest

Answer 14

Seeds turn from green to brown and become crunchy. As the berries ripen, pulp separates from seeds more easily, the fruit seems juicier, and skins become softer and chewier. Berries soften and become susceptible to dehydration. The stems lignify, turning from green to brown, and berries become easier to remove.

Question 15

foulage

Answer 15

crushing

Question 16

maceration a froid

Answer 16

cold soaking. Red grape must is held at low temperature (close to 0ºC) prior to fermentation, typically for 2 to 10 days. fruit enzymes break down the grape skins, beginning the extraction process, Believed by some to enhance color extraction.

Question 17

égrappage, éraflage

Answer 17

de-stemming

Question 18

égouttage, écoulage

Answer 18

draining. Removing the wine from the fermentation tank, leaving skins and seeds behind. Often occurs just after primary fermentation.

Question 19

collage

Answer 19

fining. The addition of a fining agent that selectively removes astringency, bitterness, proteins, or reductive aromas from the wine.

Question 20

levurage

Answer 20

inoculation

levures = yeast

Question 21

microbullage

Answer 21

or micro-oxygenation. adds small amounts of oxygen to wine post fermentation to accelerate maturation

Question 22

Species of lactic acid bacteria preferred to complete malolactic fermentation?

Answer 22

Oenococcus oeni

LAB produce wine aroma and flavor compounds, including acetic acid, acetaldehyde, diacetyl, and others

Question 23

gène

Answer 23

marc / pomace- skins and seeds left after pressing

Question 24

remontage

Answer 24

pumpover

Question 25

pigéage

Answer 25

punchdown

Question 26

déléstage

Answer 26

rack and return

Question 27

soutirage

Answer 27

racking

Question 28

which yeast is responsible for alcoholic fermentation in wine?

Answer 28

Saccharomyces cerevisiae

Question 29

échantillage

Answer 29

sampling from barrel or tank

Question 30

ouillage

Answer 30

topping- Filling barrels to replace wine lost through evaporation during barrel aging. Typically done every two to four weeks.

Question 31

décuvage

Answer 31

tank digoug. After a tank has been drained, the remaining solids are transferred to the press

Question 32

bouchon

Answer 32

cork

Question 33

béton

Answer 33

concrete

Question 34

brouillard

Answer 34

fog

Question 35

chapeau

Answer 35

cap

Question 36

chai

Answer 36

cellar

Question 37

corps étrangers

Answer 37

MOG

Question 38

cuivre

Answer 38

copper

Question 39

grappe entière

Answer 39

whole cluster fermentation

Question 40

Saccharomyces bayanus

Answer 40

Found on winery surfaces and in small numbers on grapes
Fermentative yeast
Alcohol and SO2 tolerant
Fructophilic (metabolizes 5-carbon sugars)
Used to restart fermentations

Question 41

semi-carbonic maceration

Answer 41

just some bunches are left whole- Juice in the bottom of the tank begins fermenting traditionally and produces carbon dioxide that induces carbonic maceration inside the intact clusters. The clusters may be broken down through cap management or foot-treading throughout the fermentation

Question 42

effects of stem inclusion

Answer 42

Stems increase the concentration of phenolic compounds (especially catechins) and potassium. When stems are included, the resulting wine is often lighter colored and more tannic, with a higher pH and lower alcohol

Question 43

rose- direct press vs maceration

Answer 43

direct press- whole red grape clusters are pressed, juice is treated like white wine

maceration or saignee- juice has a short period of skin contact. generally a byproduct of red winemaking, meant to concentrate the must. this juice is usually sweeter and less acidic than juice from grapes harvested for rose specifically

Question 44

why use thermovinification?

Answer 44

if botrytis is present- the quick exposure to heat can denature laccase, prevent premature oxidation. can also help with smoke taint and an excess of pyrazines.

flash détente can also accomplish this

Question 45

thermovinification vs flash détente

Answer 45

In thermovinification: must heated to 140 to 180F for 30 min - 24 hr, with higher temperatures requiring less time. The must is often pressed directly after heating, and fermentation proceeds off of skins.

With flash détente, grape must is heated rapidly to near-boiling temperatures (185 degrees Fahrenheit), then cooled rapidly using a vacuum. results in complete destruction of the berries on a cellular level—it resembles jam. The treated must is usually settled overnight, drained, and pressed, and fermentation takes place off of the skins.

The wine produced using these techniques is fruity and accessible, with jammy flavors. Very little tannin is extracted with either method, and tannin is systematically added prior to or after heat treatment.

Question 46

free run

Answer 46

juice liberated without the application of pressure. liquid drawn off the must prior to pressing

note- most of red wine is free run, press wine represents around 20% of the total volume

Question 47

two main categories of wine press

Answer 47

batch (i.e. basket, pneumatic)
continuous

Question 48

basket press

Answer 48

Pressure is applied to the lid, and the grapes are compressed slowly, releasing juice. Today, basket presses are used more often for reds than whites, since the pressure applied is uneven and results in low yields when used on unfermented berries

Question 49

pneumatic press types

Answer 49

A bladder press has an inflatable cylindrical bladder in the center of the press that expands radially, compressing the grapes symmetrically against the tank’s sides.

A membrane press is similar, but the inflatable bladder is located along one side of the tank and grapes are compressed against the other side.

A tank press is a fully enclosed membrane press that allows the winemaker to exclude oxygen for very reductive winemaking. This may be preferred for bright and clean white wine styles with delicate aromas, like popular styles of Sauvignon Blanc

Question 50

methods of clarifying juice after pressing

Answer 50

• débourbage
• floatation- gas pumped into juice so solids float to top
• bentonite clay added- it attracts proteins through electrostatic forces, does not dissolve, is removed in racking

Question 51

must adjustments- potential alcohol

Answer 51

grapes not ripe enough: chaptalization with sugar, adding rectified grape must

too ripe: diluting with water- before or after fermentation, irrigation right before harvest

Question 52

must adjustments - acidity

Answer 52

not enough acid- tartaric acid can be added- it doesn’t break down during fermentation. malic and citric can also be used

too much- deacidification. several methods involving adding salts that react with tartaric acid to form tartrate salts that settle out of the wine

Question 53

must adjustments - tannin

Answer 53

tannin can be added to improve deficiencies, stabilize color, and improve a wine’s tannin structure

it reduces the oxidative impact of botrytis, as well as the sensory impact of pyrazine and other off-aromas, including smoke taint

Question 54

non-saccharomyces yeast

Answer 54

Hanseniaspora (Kloeckera), Candida (Metschnikowia), and Torulaspora. These yeasts are often present at the beginning of fermentation, but most are not very alcohol tolerant, and their populations decline once alcohol begins accumulating

Zygosaccharomyces, Saccharomycodes, and the notorious Brettanomyces bruxellensis (Dekkera bruxellensis) are spoilage yeasts- more heat tolerant, so they are dominant toward the end of fermentation

Question 55

important bacteria in winemaking

Answer 55

lactic acid bacteria- many types are inhibited at alcohol levels above 8%. Oenococcus oeni is preferred- is is alcohol and low pH tolerant, and less likely to create VA aromas. found on grapes and in wineries, and can also be added

acetic acid bacteria- converts alcohol to acetic acid (vinebar). sulfur dioxide and limiting exposure to oxygem keep it at bay

Question 56

what nutrients does yeast require during fermentation?

Answer 56

oxygen- helps build healthy cell walls so it can survive in a high alcohol environment

nitrogen- low levels are associated with yeast’s production of hydrogen sulfide (H2S), a reductive thiol that smells like rotten eggs, and stuck fermentations

yeast assimible nitrogen (YAN) should be at 200 or more (sum of ammonia and amino acids present in the juice). diammonium phosphate (DAP), an easy-to-metabolize form of nitrogen can be added

Question 57

reductive wine

Answer 57

• Low levels of nutrients, high temperature, and other stressful fermentation conditions will favor the production of sulfides
• All yeasts produce some H2S during fermentation, but some strains produce more than others.
• At low concentration, these compounds can be responsible for “positive reduction” (matchstick, flint) and can add complexity to wine, while higher levels cause unpleasant reductive aromas (eggs, skunk, rubber, cabbage, garlic, sewage).

reductive winemaking = reducing exposure to oxygen, to preserve delicate aromatics.

only the action of yeast gives the flinty, matchstruck “reduction” aromas. however, a lack of oxygen for the yeast early on can encourage sulfide production, and exposure to oxygen later can mask some unpleasant aromas

Question 58

temperature of fermentation?

Answer 58

white wine: mid 40s-mid 60s F

red wine: mid 70s to low 90s F

yeast can survive and work between 45 and 95 F

Question 59

purpose of cap management

Answer 59

helps to regulate the fermentation temperature by breaking up hot and cold pockets, keeps the cap from drying out, and discourages the growth of acetic acid bacteria. It can also be used to introduce oxygen into the fermentation for yeast health

Question 60

battonage

Answer 60

or lees stirring.
- Toward the end of primary fermentation, stirring may be used to keep yeast in suspension and encourage the fermentation to finish.
- Stirring is also employed during wine aging to improve mouthfeel by incorporating mannoproteins, which are proteins found in yeast’s cell walls, and other products of yeast autolysis.

• The presence of yeast creates a reductive aging environment, and bâtonnage introduces oxygen that is consumed by the yeast. In general, stirring keeps the lees fresh and reduces reductive aromas.

Question 61

how to prevent malo?

Answer 61

wine is sulfured as soon as possible following primary fermentation and is almost always sterile-filtered prior to bottling to prevent refermentation in bottle.

Question 62

French oak species

Answer 62

Quercus robur and Quercus petraea (or Quercus sessilis),

coarser grained, more tannic

Question 63

American oak species

Answer 63

Quercus alba

denser, with less tannin and a higher concentration of oak lactones, resulting in more vanilla and coconut flavors

Question 64

French oak forests

Answer 64

oak from the forests of Tronçais, Allier, and Jupilles are tighter grained,

Nevers and Bertranges are medium grained, and Vosges is looser grained.

Oak from Limousin is Q. robur-dominant, coarse grained, and often preferred for spirits over wine.

Question 65

humidity and barrel aging

Answer 65

Wine aged in a cave with a relative humidity of around 70% will lose alcohol and water in the same proportion.

If the relative humidity is higher than 70%, the alcohol level will decrease through aging.

Alternately, if the relative humidity is less than 70%, alcohol will increase.

Question 66

benefits of SO2

Answer 66

anti-microbial and highly effective at inhibiting bacteria and some non-Saccharomyces yeast, though Saccharomyces and Brettanomyces have higher tolerances and may not be disabled completely by SO2.

reduces impact of oxidation by binding with products of oxidation, and acetaldehyde

bound SO2 = SO2 that has bound to sugar, tannin, acetaldehyde, etc

free SO2 = what protects the wine

Question 67

types of tannin fining agents

Answer 67

casein (milk), albumin (egg whites), isinglass (fish swim bladder), and gelatin (tendons and muscles).

Alternatively, PVPP and nylon are synthetic, vegan fining agents used to remove small phenolic compounds that cause bitterness and browning in white wine.

Fining is more prevalent in cooler regions, where fruit is harvested less ripe and tannins may be underripe or rustic.

Question 68

bentonite fining

Answer 68

bentonite is a clay that is used in white winemaking both for clarification and removing solids, and also for binding to proteins before bottling so the wine is protein stable.

small fluctuations in heat after bottling can make proteins in wine less soluble, and the wine can become hazy. removing these ensures the wine stays clear

Question 69

copper fining

Answer 69

removes unpleasant thiols, or mercaptans, that cause reductive aromas (rotten eggs, onion, garlic, skunk) in wine. these aromas originate from unhealthy yeast during fermentation and aging

Question 70

cold stabilization

Answer 70

When wine is chilled, the solubility of tartrate salts in the wine decreases, forcing them to precipitate out of solution. In many wines, potassium bitartrate and, to a lesser extent, calcium bitartrate, known colloquially as tartrates, are important examples of this phenomenon. Often, a wine is saturated, or at maximum capacity, with these tartrate salts. When the temperature is reduced, the tartrates become less soluble and form crystals.

Question 71

preventing oxidation in barrel

Answer 71

regular topping up
SO2 additions

Question 72

how to stop fermentation

Answer 72

either by temperature reduction and sulfur addition, which inhibits the yeast, or

through filtration or centrifugation, which remove the yeast.

Fortification with a high-proof spirit is another option to arrest fermentation