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WSET® Level 4 Wine > WSET® Level 4 D1 Wine Production > D1 Vinification - Winemaking, Fermentation, Adjustments > Flashcards

D1 Vinification - Winemaking, Fermentation, Adjustments Flashcards

Detailed steps of the first phases of winemaking.

1
Q

What is wine made of (what are its components)?

A
  1. Water;
  2. Alcohol;
  3. Acids;
  4. Aromatic compounds;
  5. Residual sugar;
  6. Glycerol;
  7. Phenolics.
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2
Q

Wine is approximately ___% water by volume.

A

85%

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3
Q

What is the predominant alcohol in wine?

A

Ethanol

Ethanol is formed during fermentation

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4
Q

What does ethanol contribute to wine?

A
  1. Sense of sweetness;
  2. Sense of bitterness;
  3. Oral warmth;
  4. Fullness of body;
  5. Mouthfeel;
  6. Aromas.
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5
Q

Wines with alcohol levels 14.5% and more increase what in wine?

And decrease what?

A
  • Increase sense of bitterness;
  • Decrease the volatility of wine aromas.
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6
Q

What are the principal acids in wine?

A
  1. Tartaric acid;
  2. Malic acid.

Both acids come from the grape itself

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7
Q

Tartaric acid and malic acid make up about ___ of the total acidity in wine.

A

2/3

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8
Q

Name two other acids found in finished wine that are produced during either fermentation (primary or malolactic – meaning, they’re not naturally occurring).

A
  1. Lactic acid;
  2. Acetic acid.
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9
Q

Volatile acidity refers to which acid in wine?

A

Acetic acid (smells like vinegar)

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10
Q

What does ethyl acetate smell like, and how is it produced?

A
  • Nail polish remover;
  • Produced when acetic acid reacts with the alcohol in wine.
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11
Q

Choose the correct answer from the options below.

High acidity in a wine will make the wine seem _____ on the palate.

  • Leaner
  • Fuller
  • More oaky
A

Leaner

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12
Q
  1. Excessive acid will make wine taste ___.
  2. Lack of acid will make wine taste ___.
A
  1. Tart
  2. Flabby
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13
Q

What is ‘total acidity’ in wine?

How is total acidity generally expressed?

A

The sum of all the acids.

Expressed in grams per liter (g/l) in tartaric acid.

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14
Q

Total acidity in wine is typically in the range of ___ – ___ g/l.

A

5.5–8.5 g/l

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15
Q

What is pH a measurement of?

A

The concentration of the effective acidity of a solution.

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16
Q

Wines typically have a pH in the range of ___ - ___.

A

3 – 4

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17
Q

The lower the pH, the more concentrated the ____.

A

Acidity

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18
Q

Low pH increases what in wine?

A
  1. Microbiological stability;
  2. Effectiveness of SO2;
  3. Wine’s ability to age.
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19
Q

What color does low pH give a red wine?

  • Bright purple flecks
  • Bright blue tints
  • Bright red color
A

Bright red color

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20
Q

There are four sources which aromatic and non-aromatic compounds in wine come from.

What are these four sources?

A
  1. Aromas from the grapes themselves;
  2. Aromas created by fermentation from the aroma precursors in grape must;
  3. Aromas of fermentation and its byproducts;
  4. Aromas from other sources (e.g. vanillin from oak, eucalyptol).
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21
Q

The aromatic compound rotundone smells like what?

A

Pepper

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22
Q

Give two examples of aroma precursors (aroma building blocks) that aren’t aromatic in the grape itself but become aromatic during fermentation.

A
  1. Thiols;
  2. Terpenes.
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23
Q

Give four examples of aromas created by fermentation and its byproducts.

A
  1. Esters;
  2. Acetaldehyde;
  3. Diacetyl;
  4. Sulfur compounds.
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24
Q

What is the ester that gives aromas of banana?

A

Isoamyl acetate

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25
Q

Select the correct response.

Esters are responsible for which of the following?

a) Many fresh and fruity aromas
b) Rotundone
c) Thiols

A

a) Many fresh and fruity aromas

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26
Q

Acetaldehyde, also known as ethanal, occurs in wine due to the oxidation of what?

What does it smell like?

A

Ethanol

Smells stale and is a fault in most wines except Fino Sherry, where it is a distinctive aroma.

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27
Q

The aroma created by malolactic fermentation that smells like butter, or movie theater-popcorn butter, is called ____.

A

Diacetyl

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28
Q

What does residual sugar contribute to wine?

A
  1. Sweetness;
  2. Body.
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29
Q

Go through the EU’s four ‘classification of sweetness’ levels in still wine.

A
  1. Dry/sec/trocken, etc.
  2. Medium dry/demi-sec/halbtrocken, etc.
  3. Medium or medium sweet/moelleux/lieblich, etc.
  4. Sweet/doux/süss, etc.
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30
Q

What are the permissible residual sugar levels for Dry/sec/trocken?

A

Up to 4 g/l RS, or not exceeding 9 g/l provided that total acidity expressed as grams of tartaric acid per liter is not more than 2g below RS content.

For example, a wine with 9 g/l RS can be labelled ‘Dry/Sec/Trocken’ if it has 7 g/l total acidity.

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31
Q

What are the permissible residual sugar levels for Medium dry/demi-sec/halbtrocken?

A

Between 4 g/l and 12 g/l RS, or up to 18 g/l provided that the total acidity expressed as grams of tartaric acid per liter is not more than 10 g below the RS content.

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32
Q

What are the permissible residual sugar levels for Medium or medium sweet/moelleux/lieblich?

A

Between 12 g/l and 45 g/l RS.

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33
Q

What are the permissible residual sugar levels for Sweet/doux/süss?

A

At least 45 g/l RS

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34
Q

What is glycerol derived from?

A

The sugar in grapes

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35
Q

What does glycerol contribute to wine?

A
  1. Smooth texture;
  2. Perception of fullness of the wine’s body;
  3. Has a slightly sweet taste.
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36
Q

Give two wine style examples that have elevated glycerol levels.

A
  1. Botrytis-affected grapes;
  2. Wines made by carbonic maceration.
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37
Q

Choose the correct answer from the options below.

Anthocyanins and tannins are _____:

  • Aromas from the grapes
  • Results from high glycerol
  • Phenolic compounds
A

Phenolic compounds

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38
Q

What are three overarching processes used in conventional winemaking?

A
  1. Temperature control (includes cold soaking);
  2. Use of additives and/or processing aids (e.g. cultured yeasts, chaptalization);
  3. Manipulations (e.g. filtration, reverse osmosis).
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39
Q

When the term ‘organic winemaking’ is used to describe how a wine is made, what exactly does the winemaker have to adhere to in order to use that term?

A
  • Making wine using certified organically-grown grapes;
  • Complying with rules that restrict or exclude certain practices during the winemaking process.
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40
Q

With regard to the addition of SO2, rules for organic wine:

  • Are the same across countries
  • Vary across countries
A

Vary across countries

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41
Q

Choose the correct answer from the options below.

Certified organic status can be issued by ____:

  • Associations, at the country level, or by the EU
  • The winemaker
  • The grape grower
A

Associations, at the country level, or by the EU

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42
Q

The EU definition of organic wine:

  • allows
  • does not allow

the addition of regulated amounts of SO2.

A

Allows

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43
Q

In the United States, the category of ‘wine made from organic grapes’

  • allows
  • does not allow

the addition of SO2.

A

Allows

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44
Q

In the United States, the definition of organic wine:

  • allows
  • does not allow

any addition of SO2.

It also requires naturally-occurring SO2 (produced in fermentation) to be less than ___ mg/l.

A

Does not allow any addition of SO2

Less than 10 mg/l

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45
Q

The main certifying association of biodynamic viticulture and winemaking is:

A

Demeter International

Demeter sets certain global standards, but Demeter certifiers in each country determine the specifications.

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46
Q

Name two products not permitted in biodynamic winemaking.

A
  1. Added tannins;
  2. Isinglass.
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47
Q

Even though there is no agreed definition for natural wine, what are some of its core practices?

A
  1. Fermentation by ambient yeasts;
  2. Wine made with the fewest possible manipulations;
  3. No added SO2 or the absolute minimum of added SO2 (typically only at bottling).
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48
Q

Can a winemaker make natural wine from conventionally-grown grapes?

A

Yes

Natural wine can be made from conventionally or sustainably grown grapes, though many natural winemakers would argue that organic or biodynamic grapes should be used.

There is no certifying body for natural winemaking; thus, any winery can claim that any of their wines are natural.

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49
Q

What are three threats that excessive oxygen exposure pose to white wine?

A
  1. Loss of fruitiness;
  2. Formation of unwanted aromas, e.g. acetaldehyde;
  3. Discoloration / turning brown.
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50
Q

Why don’t red wines suffer the negative effects from oxygen the same way white wines do?

A

Red wines have higher levels of phenolic compounds, which absorb oxygen and have an anti-oxidative effect on the wine.

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51
Q

The practice of minimizing oxygen exposure during the winemaking process is called _____ winemaking.

A

Reductive (or protective)

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52
Q

List five ways to minimize oxygen exposure in reductive winemaking.

A
  1. Avoiding ullage, which is the headspace of air between the wine and the top of the container;
  2. Use inert gas to flush out oxygen from vessels, pipes and machinery, or fill the ullage in containers and vessels;
  3. Add SO2;
  4. Use impermeable containers, such as stainless steel or concrete, and screw caps;
  5. Maintaining cool, constant temperatures which slow the rate of oxidation reactions.
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53
Q

Some producers believe exposing their white wines to oxygen before fermentation leads to greater ___ ___ in the wine, increasing age potential.

A

Oxidation stability

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54
Q

What are some ways winemakers can increase oxygen exposure during the winemaking process?

A
  1. Cap management techniques in red wine fermentation that spray or splash the must;
  2. Use of small wood barrels that contain a small volume of wine relative to the ingress of oxygen through the bung holes and staves;
  3. Increasing the number of rackings or amount of lees stirring during aging;
  4. Allowing ullage;
  5. Not using inert gases;
  6. Techniques that involve pumping oxygen through the must or wine (e.g. micro-oxygenation)
55
Q

What is a wine at risk of developing if it sees some oxidative techniques, has some residual sugar, and is fermented at warmer temperatures?

A

Spoilage microbes such as Brettanomyces or acetic acid bacteria.

Bottom line: winemakers must be judicious about oxygen exposure.

56
Q

What are the two key properties of sulfur dioxide?

A
  1. Anti-oxidant;
    • ​​SO2 inhibits oxidative enzymes;
    • SO2 reduces the effects of oxidation by reacting with the products of oxidative reactions, so they cannot oxidize further compounds in the wine;
  2. Anti-microbial;
    • ​​SO2 inhibits the development of microbes such as yeast and bacteria.
57
Q

Choose the correct answer from the options below.

Sulfur dioxide comes in ____:

  • One form only: gas
  • Two forms: liquid and solid
  • Various forms including gas, liquid, solid, and others
A

Various forms: gas, liquid or solid, potassium metabisulfite or potassium bisulfite

58
Q

How much SO2 is naturally produced during fermentation?

A

10 mg/l or less

59
Q

In the EU, what are the maximum concentration levels of SO2 for red wines and for white wines?

A

Red wines: 150 mg/l

White wines: 200 mg/l

60
Q

If a wine contains over ____ mg/l SO2, the label must state that the wine contains sulfites.

A

10 mg/l

61
Q

What is meant by ‘bound SO2’?

A

SO2 that has been added to must or wine that dissolves and reacts with compounds in the liquid; it becomes ineffective against oxidation and microbes because it is “bound” to those compounds.

62
Q

What is meant by ‘free SO2’?

A

Unbound SO2 that is the most effective against oxidation and microbes.

63
Q

Why would a greater amount of SO2 be needed for musts and wines with relatively high pH?

A

The pH level of a must or wine has a key effect on the efficacy of SO2.

At lower pH levels (higher acidity) there is a greater proportion of free SO2; conversely, at higher pH levels (lower acidity) there is a lower proportion of free SO2, so more SO2 is needed to protect the wine against microbes and oxidation.

64
Q

Which is considered the more effective application of SO2:

  • Adding a larger amount when the grapes are crushed, at the end of malolactic conversion, and at bottling.

OR

  • Adding smaller amounts throughout the winemaking process.
A

Adding a larger amount when the grapes are crushed, at the end of malolactic conversion, and at bottling.

65
Q

Potassium metabisulfite is a form of SO2 that is best used how?

A

Added to grapes to protect them from oxidation and microbial spoilage when they are picked and put into hoppers for transport to the winery.

66
Q

Because grapes are more vulnerable to oxidation and bacteria at higher temperatures at time of harvest, what are some measures winemakers can take to minimize these risks?

A
  1. Harvesting grapes at night or at sunrise when temperatures are lower;
  2. Adding SO2 to the grapes after they’re picked;
  3. Lowering the grapes’ temperature by putting them in a cold storage room once received at the winery;
  4. Sanitizing harvest equipment and bins.
67
Q

Name three ways to get your grapes cool prior to crushing.

A
  1. Harvest at night or at sunrise when temperatures are at their coolest;
  2. Chilling grapes in a refrigeration unit after picking;
  3. Using a heat exchanger.
68
Q

What is the range of sorting options employed by grape growers or winemakers?

A

Removing undesirable grapes/bunches before picking or during hand-harvesting;

By hand at the sorting table, which can take place before or after destemming;

Optical sorting, which is a high-tech, high-cost option that uses digital imaging and software technology to scan individual grapes.

69
Q

If stems are not ripe, what can they impart on wine?

A
  • Unwanted green flavors;
  • Bitter tannins.
70
Q

Give three examples when winemakers keep bunches whole.

A
  1. Partial whole bunch fermentation (e.g. Pinot Noir in Burgundy);
  2. Carbonic maceration (e.g. Gamay in Beaujolais);
  3. Whole-bunch pressing for some white wines and premium sparkling wine.
71
Q

What is the difference between crushing and pressing?

A

Crushing – the application of sufficient pressure to the grapes to break the skins and release the juice.

Pressing – the separation of the juice or wine from the skins and seeds (want to press softly so the bitter tannins are not extracted from the seeds or skins yet maximize release of juice).

72
Q

If a winery uses only a destemmer–crusher machine, when is their opportunity to sort?

A

Only at the whole-bunch level – the grapes will not go on a sorting table.

73
Q

In winemaking, ‘must’ refers to:

  • The substance that is being fermented
  • The machine that destems the grapes
  • The type of sulfur used after grapes are put into the hopper
A

The substance that is being fermented

74
Q

In white winemaking, grapes are pressed before or after fermentation?

A

Before

75
Q

In red winemaking, red grapes are pressed before or after primary fermentation?

A

After

76
Q

What are the two most popular presses used in winemaking?

A
  1. Pneumatic press (also known as ‘air bag press’);
  2. Basket press (also known as ‘vertical press’).
77
Q

Why can’t winemakers use inert gases with basket presses?

A

Because they’re not sealed vessels

78
Q

Why is the continuous press best suited to producing inexpensive, high-volume wines?

A

While less gentle than the pneumatic and basket presses, the continuous press allows grapes to be continually loaded into the press because it works by using a screw mechanism; this allows for quicker pressing of large volumes of grapes.

79
Q

What is pomace?

A

The grape solids that remain after pressing

80
Q

List five common practice must adjustments.

A
  1. Enrichment;
  2. Reducing alcohol;
  3. Acidification;
  4. Deacidification;
  5. Adding powdered tannins.
81
Q

What are some of the enrichment additives used to adjust musts?

A
  • Dry sugar (also known as chaptalization);
  • Grape must;
  • Grape concentrate or rectified concentrated grape must (RCGM).
82
Q

What are the two types of dry sugar used in chaptalization?

A
  1. Beet sugar;
  2. Cane sugar.
83
Q

Warmer areas of Europe are not allowed to add dry sugar as an enrichment.

Which enrichment sugar are they allowed to add?

A

RCGM (rectified concentrated grape must), but within limits

84
Q

What is the maximum enrichment percentage allowed in:

Cool areas of the EU (Zone A)

Warm areas of the EU (Zone CIIIb)

A

Zone A (cool areas): 3%

Zone CIIIb (warm areas): 1.5%

85
Q

When is sugar usually added as an enrichment?

A

When fermentation has started as the yeasts are active

86
Q

Another way to concentrate sugars in wine is by removing the water from wine.

What are the three ways to remove water from wine?

A
  1. Reverse osmosis;
  2. Vacuum evaporation;
  3. Cryoextraction (usually the least expensive).
87
Q

What are three ways to reduce or remove alcohol in wine?

A
  1. Adding water (this can dilute aromas and flavors, and isn’t legal everywhere);
  2. Reverse osmosis;
  3. Spinning cones.
88
Q

How does reverse osmosis work?

A

It’s a form of cross-flow filtration.

The wine is pushed through an extremely tight filter that only water and alcohol can pass through. That water-alcohol mixture is distilled to separate the alcohol from the water, and whatever is left from the water-alcohol solution is put back into the wine.

The equipment can be rented or bought, but is generally expensive.

89
Q

How do spinning cones work?

A

It’s a device that fractionates wine, first removing volatile aroma compounds followed by alcohol.

After these are removed, they’re blended back into the wine to the desired level.

This is extraordinarily costly, so only very large firms have them.

90
Q

What are some reasons a winemaker would acidify their wine?

A
  1. To lower the pH;
  2. Add freshness and balance if malic acid is low.
91
Q

What are the acids used in acidification?

A
  1. Tartaric;
  2. Citric (not allowed in the EU);
  3. Malic;
  4. Lactic.
92
Q

When is lactic acid used to acidify wine?

A

After malolactic conversion; it’s less harsh than the other acids

93
Q

When do winemakers typically prefer to acidify their wine?

Why?

A

Before fermentation starts

The must will start off with a lower pH, and most winemakers feel that starting fermentation with adjusted acidity makes for better integration and a more complete result.

94
Q

Within the EU, winemakers are:

  • allowed to both chaptalize and acidity musts
  • not allowed both to chaptalize and to acidify musts
A

Not allowed both to chaptalize and to acidify musts

95
Q

How are wines deacidified?

A
  1. By adding calcium carbonate (chalk) or potassium carbonate;
    • these lower acidity by forming tartrates and their subsequent precipitation out of the wine;
  2. Ion exchange;
    • high tech and expensive.
96
Q

How are powdered tannins used as a must adjustment?

When are they added?

A
  1. To help to clarify the must;
    • in red wines, they also help stabilize color and improve mouthfeel.
  2. Added to must before fermentation or added to wine before maturation.
97
Q

The environment in which alcoholic fermentation happens is:

  • aerobic
  • anaerobic
A

Anaerobic (without oxygen)

To be clear, yeasts initially need oxygen in order to multiply, but once the yeasts use up that oxygen they switch to fermentation in that anaerobic environment.

98
Q

Describe the optimal fermentation environment for yeasts.

A
  • Viable temperature range*;
  • Access to yeast nutrients, particularly nitrogen;
  • Absence of oxygen.

Winemakers prefer a relatively warm start to fermentation (e.g. 25°C / 77°F) to establish the yeast population

99
Q

Fermentation is:

  • an endothermic process (absorbs heat and cools its surroundings)

OR

  • an exothermic process (releases heat and heats its surroundings)
A

An exothermic process (releases heat and heats its surroundings)

100
Q

Besides alcohol, carbon dioxide and heat, what else does fermentation produce?

A
  1. Volatile acidity;
  2. Small amounts of naturally-produced SO2;
  3. Aromatics from aroma precursors, which are released by the action of yeast and create aromas in wine;
  4. Aromatics created by yeast (e.g. esters/fruity flavors);
  5. Glycerol, which increases the body of the wine.
101
Q

What is the most common species of yeast used in winemaking?

A

Saccharomyces cerevisiae

102
Q

What are some of the positive characteristics of Saccharomyces cerevisiae?

A
  • Able to withstand well the high acidity and increasingly high alcohol level of the must as it ferments;
  • Fairly resistant to SO2 compared to other yeast species;
  • Reliably ferments musts to dryness;
  • Several strains exist within the species so winemakers can select a strain for a particular outcome.
103
Q

What are the two categories of yeasts used by winemakers?

A
  1. Wild (also known as ambient);
  2. Cultured.
104
Q

Where do ambient yeasts live?

A
  • In the vineyard;
  • In the winery.
105
Q

What are the advantages of using ambient yeasts?

A

No cost;

Can add aromatic complexity thanks to the number of yeast species making different aroma compounds;

Recent studies have shown that the dominant yeast population in a must is unique to a place or region, thus supporting the idea that yeast strain contributes to the individuality of wines or even the terroir of a wine;

May be used for the marketing of the wine.

106
Q

What are the disadvantages of using ambient yeasts?

A

Fermentation may start off slow, which is dangerous in developing volatile acidity and the growth of spoilage organisms, potentially leading to off-flavors;

Fermentation to dryness may take longer, which may not be suitable for a high volume winery;

Increased risk of a stuck fermentation, leaving the wine open to spoilage organisms;

Consistency cannot be guaranteed, which can be a drawback for producers looking for consistency over many large vessels or across vintages.

107
Q

Commercially available cultured yeasts are often single strains of which yeast strain?

A

Saccharomyces cerevisiae

108
Q

When a winemaker wants to use cultured yeast for their fermentation, how do they incorporate it?

A
  1. Cool the must to prevent fermentation by ambient yeast and then add the cultured yeast, which quickly overwhelms the natural yeast population;
  2. Add SO2 to the must to suppress ambient yeasts. A starter batch, made up of fermenting grape must activated with the cultured yeast the winemaker wants to use, is then added to the tank of must to be fermented.
109
Q

What are the advantages of using cultured yeasts?

A

Reliable, fast fermentation to dryness;

Low levels of volatile acidity and, because they work fast and are reliable, there is less danger from spoilage yeasts and bacteria;

Help produce consistent product from one vintage to the next;

Wide selection of strains available commercially, so winemaker’s selection can affect the style of wine.

110
Q

What are the disadvantages of using cultured yeasts?

A

Some speculate that using cultured yeast results in a certain sameness of fruit expression across wines; a term some people use is ‘industrial wine’;

Using cultured yeast adds to costs.

111
Q

Low levels of ____ in the must can lead to a stuck fermentation.

A

Nitrogen

112
Q

The following two yeast nutrients can be added to help restart stuck ferments:

  • Diammonium phosphate (DAP) and/or thiamine (vitamin B1)
  • Saccharomyces cerevisiae or Brettanomyces
  • 4MMP or SO2
A

Diammonium phosphate (DAP) and/or thiamine (vitamin B1)

113
Q

The speed of fermentation is related to the ___ of the must.

A

Temperature

This in turn affects the style of wine being produced.

114
Q

If a winemaker wants to make a less fruity white wine or an easy-drinking fruity red wine with low tannins but still fruity, around what temperature would they ferment the must?

A

17–25°C / 63–77°F

115
Q

If a winemaker wants to make a powerful red wine, extracting the maximum color and tannins from the grapes, at what temperature would they initially ferment the must?

A

26–32°C / 79–90°F

116
Q

If a winemaker wants to make a white or rosé wine that retains fresh and fruity aromas and flavors, around what temperature would they ferment the must?

A

12–16°C / 54–61°F

117
Q

What is the high temperature at which yeasts struggle to survive?

A

35°C / 95°F

Above this temperature, yeasts will slow or stop fermenting

118
Q

What are some ways to change a fermentation’s temperature?

A
  • If ferment is in small enough vessels, they can be moved to warmer spots in the winery (if it’s sluggish) or to cooler spots (if it’s overheating);
  • Cooling jackets;
  • Inserts;
  • Pumping over or délestage (racking) to release heat.
119
Q

What are the three most common fermentation vessels made of?

A
  1. Stainless steel;
  2. Concrete;
  3. Wood.
120
Q

Name two other materials used for fermentation vessels.

A
  1. Plastic bins (also known as T-Bins);
  2. Terracotta vessels.
121
Q

Give three names for terracotta vessels.

A
  1. Amphora;
  2. Qvevri (Georgia);
  3. Tinaja (Spain).
122
Q

What are the advantages to using stainless steel vessels?

A
  1. Easy to clean, hygienic;
  2. Come in a range of sizes;
  3. High degree of control over the temperature of the must or wine;
  4. Protect the wine from oxygen;
  5. Neutral (do not add any flavors);
  6. High level of mechanization possible (e.g. automatic pump-over, temperature control).
123
Q

What is a disadvantage to using stainless steel vessels?

A

The initial financial investment of the tanks and their accompanied computerized temperature-control systems is high.

124
Q

Discuss two desirable features of concrete vessels.

A

They maintain an even temperature much more efficiently than stainless steel;

Smaller, egg-shaped concrete vessels, which are very expensive, are said to set up convection currents that mix the fermenting must and mix the lees during maturation (like a natural lees stirring).

125
Q

Why is it rare for red wines to be fermented in small wooden barrels?

A

Difficult to manage the cap

126
Q

What are some of the advantages of using wood barrels for fermentation?

A
  • Wood retains heat well;
  • Some winemakers feel that wines benefit from the small amount of oxygen that fermenting in oak provides;
  • Can be reused many times, so are more affordable over the long term.
127
Q

What are the disadvantages of using wood barrels for fermentation?

A
  • Must be diligent with hygiene as the pores in wood can hide bacteria and spoilage organisms;
  • Require capital investment when new large oak casks are bought.
128
Q

What happens during malolactic conversion?

A
  • Lactic acid bacteria converts malic acid into lactic acid and carbon dioxide;
  • Malolactic conversion produces heat.
129
Q

Name three conditions that encourage malolactic conversion.

A
  1. Temperature between 18–22°C (64–72°F);
  2. Moderate pH (3.3–3.5);
  3. Low total SO2.
130
Q

Name six conditions that inhibit malolactic conversion.

A
  1. Temperature below 15°C (59°F);
  2. Low pH;
  3. Moderate levels of SO2;
  4. Adding lysozyme (an enzyme that kills lactic acid bacteria);
  5. Moving a batch of wine going through malo to another part of the winery to avoid the spread of lactic acid bacteria;
  6. Filtering out lactic acid bacteria to avoid malolactic conversion from taking place.
131
Q

What are the results of malolactic conversion?

A
  1. Reduction in acidity + rise in pH;
  2. Color loss (in red wines);
  3. Increased microbial stability;
  4. Slight flavor shift (buttery notes from diacetyl);
  5. Slight increase in volatile acidity.
132
Q

What are the advantages of promoting malolactic conversion to happen at the same time as alcoholic fermentation?

A
  • Increase fruity characteristics;
  • Reduce production times, saving money as wines are finished and sold earlier.
133
Q

What are the advantages of malolactic conversion occurring in barrel?

A
  • Ability to stir the lees at the same time as malo is happening;
  • Promotes better integration of the flavors.
134
Q

What is MegaPurple and why would a winemaker add it to their wine?

A
  • It’s a grape-derived coloring agent;
  • It enhances color intensity.

WSET® Level 4 D1 Wine Production (11 decks)

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