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WSET Level 4 D1 by Chapter > Level 4 D1 Chap 13 - General Winemaking Options > Flashcards

Level 4 D1 Chap 13 - General Winemaking Options Flashcards

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1
Q

What impact does the presence of oxygen have on wine?

A

Oxygen typically breaks down many flavours that make fresh, fruity wines. e.g. thiols in Sauvignon Blanc

Oxidation typically creates nutty/ savoury flavours, e.g. acetaldehyde

White wines become darker and browner

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2
Q

What compounds may help protect against the presence of oxygen in still wine?

A

Phenolic compounds in red wine are anti-oxidative

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3
Q

How are oxygen levels limited in winemaking?

A
  • Avoid ullage in vessels; fill to the top and use tight seals
  • Use inert gases to flush out oxygen/air from equipment before it makes contact with wine
  • Add sulphur dioxide, which is anti-oxidative
  • Use impermeable containers for processing and with bottles: stainless steel and concrete over wood; screw cap over cork
  • Keep temperatures lower
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4
Q

When is oxygen required in winemaking?

A

At the start of fermentation, oxygen promotes healthy yeast growth

Early exposure may increase the stability of white wine to oxygen increasing ageing potential

In red wine oxygen is required for the reactions between anthocyanins and tannins that stabilises colour

Some oxygen exposure derived compounds may give desired characteristics: dried fruits, honey, caramel, coffee, leather, mushrooms

Some fortified wine requires oxygen: Oloroso, Madeira, Tawny port

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5
Q

How is oxygen exposure increased during winemaking?

A

Cap management techniques that spray/splash wine

Smaller wooden barrels

Increased rackings / lees stirring

Allow ullage in containers

Pump oxygen through (micro-oxygenation)

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6
Q

What properties does sulphur dioxide have in winemaking?

A

Anti-oxidant (indirect)

Anti-microbial

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7
Q

What SO2 levels are permitted by the EU?

A

150 mg/l in red wine
200 mg/l in white wine
Over 10 mg/l requires a label that the wine contains sulphites

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8
Q

How can winemakers reduce SO2 requirements?

A
  • Limiting oxygen exposure during winemaking
  • Lower temperatures during winemaking
  • Good hygiene and grape sorting limit microbes
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9
Q

What states does SO2 exist in wine and how can these be influenced?

A

Bound SO2 has reacted with compounds in the wine and has limited benefits

Free SO2 is either inactive (most) or molecular (limited proportion).

Molecular SO2 is most beneficial. Greater proportions exist at lower pH

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10
Q

How are grapes and must protected in harvest and transportation?

A

Pack in smaller crates to protect against crushing

Keep temperatures lower - harvest at night

Add SO2 (potassium metabisulfite)

Keep equipment clean / sanitised

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11
Q

What processes may a grape be exposed to before fermentation?

A 
Chilling
Sorting, or triage
Destemming
Crushing
Pressing
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12
Q

How can grapes be sorted?

A
  • Remove unwanted grapes/bunches before harvest
  • Sort by hand - on a table, a conveyer belt, or a vibrating belt (also removed MOG)
  • Optical sorting
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13
Q

What are the implications of increasing sorting?

A

Increasing sorting, typically

  • increases cost, and
  • lowers yields as more grapes are removed.

It may be required in poor years, if there are larger number of unripe or moldy grapes

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14
Q

Why are some grapes not de-stemmed?

A

It depends on the wine being made:

  • Some red wine fermentations use whole bunches, which increase tannin levels from stems (stems need to be ripe)
  • carbonic maceration needs whole bunches
  • some white wines and sparkling wines require whole bunch pressing
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15
Q

Explain crushing vs. pressing

A

Crushing breaks the skin of grapes and releases juice to instigate fermentation. Care is taken to leave seeds whole. Can be carried out by feet.

Pressing is the separation of juice or wine from skin and seeds

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16
Q

What are the common types of press?

A

Pneumatic press uses and air sack in a tank to apply pressure to grapes. Investment is greater, but the pressure control is greater and inert gas flushing can be carried out.

Basket press (also vertical or Champagne press) is unsealed, possibly more gentle that a pneumatic press, but more labour intensive as they hold a smaller load

Horizontal screw press is similar to a basket press

Continuous presses, which are better suited to high volume, inexpensive wine

17
Q

What is the name for solid remains left over pressing?

A

Pomace

18
Q

What are the common adjustments made to must?

A

Enrichment (chaptalisation, concentration, RCGM addition)

Reducing alcohol (dilution)

Acidification (4 types of acid commonly added: Tartaric, malic, citric, lactic)

Deacidification (2 compounds commonly added: potassium carbonate, calcium carbonate)

19
Q

What practices are covered by the term ‘enrichment’?

A

Chaptalisation - adding dry sugar

Concentration of sugar levels

  • reverse osmosis
  • vacuum extraction
  • chilling

Adding RCGM or other grape products

20
Q

What level of chaptalisation is allowed in the EU?

A

1.5% to 3%

It depends on the area:
- Cooler regions may add up to 3% (to a maximum of 11.5% in white and 12% in red)

  • Warmer regions may add up to 1.5%, and are limited to grape concentrate or RCGM
21
Q

How is alcohol reduced prior to fermentation?

A

Typically dilution with water, although the practice is tightly controlled. Aromas and flavours are also diluted

22
Q

How and when is acidification carried out?

A

Tartaric acid is usually added, although citric (not in the EU), malic and lactic acids can also be added

Acidification can happen at any point, although typically before fermentation

23
Q

What level of de-/acidification is allowed in the EU?

A

-1 g/L to 2.5g/L

It depends on the area:

  • In cooler climates, deacidification of up to -1 g/l is allowed
  • In warmer climates, acidification of up to 2.5 g/l is allowed
24
Q

Why do winemakers acidify must/wine?

A

In warmer climates, malic acid levels may drop dramatically during ripening

With too little acid, wine may lack freshness.

25
Q

How is deacidification carried out?

A

Calcium carbonate or potation carbonate is added, which precipitates tartrates out of the must/wine

If deacidication is carried out prior to fermentation, the winemaker must bear in mind some further reduction in acid may take place due to MLF

26
Q

What COMPOUNDS are produced during fermentation?

A

Yeast primarily convert sugar into alcohol and carbon dioxide, in the absence of oxygen

Other compounds include:

  • small amounts of volatile acid
  • small amounts of SO2
  • aromatics from aroma precursors (e.g. thiols like 4MMP)
  • aromatics from yeast (e.g. esters that give fruity flavours)
  • glycerol
27
Q

What species of yeast are used by wine makers?

A

Saccharomyces cerevisiae is the most common due to its resistance to SO2 and alcohol levels

Saccharomyces bayanus is used for higher alcohol content, or re-fermenting sparkling wine

28
Q

What yeast sources are there?

A

Ambient yeast - mixed yeast varieties that live on grapes and in the winery, although S. cerevisiae is dominant over 5% alcohol

Cultured yeast from a laboratory can be selected for different characteristics. e.g. enhancing aromatics, or retained fruit

29
Q

List the advantages and disadvantages of ambient yeast for fermentation

A

Advantages:

  • increased complexity of aroma compounds
  • unique varieties may lead to unique expressions of terroir
  • free
  • marketing tool

Disadvantages:

  • risk of spoilage yeasts (brettanomyces) and bacteria
  • fermentation may take longer or get stuck
  • variable product / consistency is nearly impossible
30
Q

List the advantages and disadvantages of cultured yeast for fermentation

A

Advantages:

  • reliable, fast fermentation
  • less danger of spoilage
  • consistent product
  • choice of strains to impact flavour

Disadvantages:

  • cost
  • potential similarity of flavours across the industry
31
Q

What are typical fermentation temperature ranges for different wine styles?

A

To get fermentation started, ideal temp is 25°C
Cool: 12–16°C for fresher fruitier white and rosé

Mid-range: 17–25°C for easy drinking red, or barrel fermented white

Warm: 26–32°C for powerful reds to maximise colour and tannin extraction

32
Q

How is temperature controlled during fermentation?

A 
Coolant jackets in stainless steel vats
Move ferments into warmer/cooler cellars
Pumping over (délestage) reduces heat
33
Q

What are different fermentation vessels normally made from and what characters do they bring?

A

Stainless steel - neutral, good temperature control, good for mechanisation

Concrete - efficient temperature control. Can be cheap, or expensive. Lined with resin

Wood - need good hygiene. Retains heat. May oxygenate more. Less common for reds due to poor cap management

34
Q

What is MLF and how does it arise?

A

Malolactic Fermentation, or conversion, is from lactic acid bacteria converting malic acid to lactic acid

Needs a temperature >15°C, a low pH and low-moderate SO2

35
Q

Which wines typically go through MLF?

A

All red wine, in combination with normal fermentation, because of the higher temperatures of fermentation

Acidic white wines in non-aromatic grape varieties, e.g. Chardonnay

36
Q

What characteristics does MLF bring to a wine?

A
  • Reduction in acidity
  • Some loss red colour
  • Greater microbial stability because MLF will now NOT happen in the bottle
  • Potential reduction of fruit character and addition of buttery notes (notably in white wine)
37
Q

What techniques can reduce alcohol post-fermentation?

A

Reverse osmosis to remove a mixture of water and alcohol - distillation can remove alcohol from this mix before adding it back

Equipment called a spinning cone

38
Q

How can colour be adjusted?

A

Fining may reduce unwanted colour

Some colours may be added, e.g. grape derived MegaPurple

WSET Level 4 D1 by Chapter (22 decks)

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