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WsetDip D1 > 18.2 Crushed Fruit Fermentations > Flashcards

18.2 Crushed Fruit Fermentations Flashcards

1
Q

In general, how are most red wines made?

A

Destemming and crushing the fruit before fermentation

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2
Q

What is the key aim of maceration before fermentation?

A

To extract colour and flavours, without extracting tannins

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3
Q

When maceration before fermentation, why are tannins not readily extracted?

A
  • Anthocyanins are soluble in both the must and wine

- Tannins are more soluble in alcoholic liquids (not readily extracted at this point)

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4
Q

What are the 2 main methods of maceration before fermentation?

A
  1. Cold soaking

2. Macerations using heat

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5
Q

What is cold soaking?

A
  • aka ‘cold maceration’, ‘pre-fermentation maceration’
  • juice and skins are chilled to reduce the rate of oxidation, microbial spoilage and spontaneous fermentation
  • cold temperatures result in a slow extraction, which can easily be monitored and controlled to achieve the level of extraction desired
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6
Q

In cold soaking, to what temperature are the juice and skins chilled?

A

4–10°C / 39–50°F

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7
Q

How long does cold soaking typically last?

A

3–7 days

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8
Q

What might a winemaker do during cold soaking?

A
  • punching down and/or pumping over to mix up the skins and juice, aiding extraction
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9
Q

What are the benefits of cold soaking?

A
  • reduce the rate of oxidation, microbial spoilage and spontaneous fermentation
  • avoids the growth of spoilage microbes that need oxygen, such as acetic acid bacteria, on the top of the cap of skins
  • gentle technique (suitable for premium wines)
  • slow extraction, which can easily be monitored and controlled to achieve the level of extraction desired
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10
Q

What grape commonly goes through cold soaking? Why?

A

Pinot Noir

  • to promote colour intensity
  • variety has a low level of anthocyanins
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11
Q

What are the costs associated with cold soaking?

A
  • energy required to chill the wine

- time taken for cold soaking (tying up valuable tank space)

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12
Q

What qualities of wines typically go through cold soaking?

A
  • not suitable for high-volume inexpensive wines
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13
Q

Why would a winemaker choose to macerate using heat?

A
  • higher temperatures lead to greater extraction
  • designed to extract high levels of anthocyanins and flavours quickly (tannins may also be extracted, but to a lesser extent)
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14
Q

What are the two key techniques to macerate using heat?

A
  1. flash détente

2. thermovinification

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15
Q

What is thermovinification?

A
  • involves heating the must to around 50–60°C (122–140°F), sometimes higher
  • time spent macerating ranges from minutes to hours
  • generally, the higher the temperature, the shorter the maceration
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16
Q

What is flash détente?

A
  • destemmed grapes are quickly heated to 85–90°C (185–194°F)
  • then rapidly cooled under a vacuum
  • process bursts the cells in the grape skins, allowing a very rapid extraction of anthocyanins and flavours
  • takes around two minutes
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17
Q

What are the costs associated with flash détente?

A
  • vacuum system is expensive to buy
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18
Q

What quality of wines typically go through flash détente? Thermovinification?

A
  • (FD) high-volume wineries where the large throughput may justify cost of vacuum system
  • (BOTH) inexpensive or mid-level wines that are going to be consumed shortly after production (colour instability issues)
  • (BOTH) blending component in higher quality wines, bringing juicy, fruity flavours to the blend
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19
Q

What are the main disadvantages of flash détente and thermovinification? Why?

A
  • colour instability issues: there is not enough tannin to bind with the anthocyanins and form more stable compounds
  • reduction in more subtle varietal characters
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20
Q

What are the other advantages of flash détente and thermovinification? Why?

A
  • can be particularly beneficial if the grapes are affected by botrytis (grey rot), as the high temperatures denature oxidative enzymes (called laccase) produced by the rot
  • flash détente can also be used as a treatment for smoke taint
  • intensify the fruitiness of the wines
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21
Q

How are the vast majority of red wines fermented?

A

On the skins

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22
Q

What is the cap?

A

In a tank of fermenting must, the grape skins typically float at the top of the liquid, buoyed by carbon dioxide.

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23
Q

Why is it important to mix the skins with the juice/wine during fermentation?

A
  • mixing promotes even extraction (the skins spend the fermentation macerating in the same small volume of liquid that surrounds them. This liquid would become saturated with colour, tannins and flavours and therefore dissolution of these compounds into the liquid would stop)
  • the cap could dry out and not contribute to the extraction
  • helps to distribute heat produced during fermentation (temperature monitoring and control)
24
Q

What are the 5 main cap management techniques?

A
  1. Punching down
  2. Pumping over
  3. Rack and return
  4. Ganimede® tanks
  5. Rotary fermenters
25
Q

How does timing of the mixing with the fermentation timing influence the extraction?

A
  • more mixing at the start of fermentation with less mixing at the end: extract more colour and less tannin
  • mixing more at the end of the fermentation: extract a greater amount of tannin
26
Q

What role does temperature play in cap management?

A
  • Warmer fermentations will extract more
  • Temperature-controlled vessels allow control over tannin extraction (e.g. cooling towards the end when more tannins could be extracted)
27
Q

Describe punching down. What is the French term?

A
  • aka ‘pigeage’ (French)
  • A plunger is used to submerge the cap of grape skins in the liquid
  • By hand or by a mechanised plunger
  • Gentle process
28
Q

For what types of wines is punching down used?

A
  • low-volume production of premium wines
  • labour intensive if done by hand
  • must be relatively small, open top vessels
29
Q

Describe pumping over. What is the French term?

A
  • aka ‘remontage’
  • Juice/wine is taken from near the bottom of the vessel and sprayed over the cap of skins
  • Extracts colour, tannins and flavours from the cap of skins as it passes through
  • Gentle process
  • usually punching down or rack and return is also required to extract enough colour, flavour and tannin
30
Q

During pumping over, what fraction of liquid is pumped and sprayed over?

A

one-third to one-half of the liquid in the vessel

31
Q

How can pumping over occur aerobically?

A

By splashing the wine into a new container and then pumping it from there up over the cap of skins

32
Q

What is the main benefit of pumping over aerobically?

A

exposes the must to oxygen

  • beneficial for yeast health
  • avoidance of reductive off-flavours (rotten eggs)
33
Q

How can pumping over occur anaerobically?

A

In closed vessels by attaching the hose to a tap at the top of the vessel or simply by keeping the hose close to the cap of skins in an open vessel

34
Q

For what types of wines is pumping over used?

A
  • all black varieties
  • wines of all price points and qualities
  • suitable for use on large vessels
35
Q

How is pumping over carried out in modern wineries?

A
  • pumps and hoses installed at each tank
  • pump-overs can be pre-programmed to occur at certain times and for certain durations
  • reduces need for labour
36
Q

What is rack and return?

A
  • aka ‘delestage’
  • similar to pumping over
  • juice pumped from one vessel into another
  • As juice is pumped out, the cap of skins falls down the vessel
  • juice then pumped from the new vessel in through the top of the original vessel, sprayed over the skins.
  • breaks up the cap and mixes the juice and skins thoroughly
37
Q

What methods of cap management are most extractive?

A

Rack and return, Ganimede® tanks, Rotary fermenters

38
Q

How many times can rack and return be carried out? Why?

A
  • only 1–3 times during the fermentation, alongside punching down and pumping over
  • very extractive
39
Q

For what types of wines is rack and return used? Give examples.

A
  • red wines where medium to high levels of flavour, colour and tannin are desired
  • e.g. Cabernet Sauvignon- or Syrah-based wines
40
Q

What are the costs associated with rack and return?

A
  • cannot be fully automated
  • requires labour to set up and monitor
  • requires a clean vessel to be available
41
Q

What is a Ganimede® tank?

A
  • specialised tanks that bubble CO2 (or O2) up through the must/wine
  • Pressure builds up under the cap, until finally the cap bursts
  • very extractive
42
Q

For what types of wines are Ganimede® tanks used? Give examples.

A
  • red wines where medium to high levels of flavour, colour and tannin are desired
  • e.g. Cabernet Sauvignon- or Syrah-based wines
43
Q

What are the costs associated with Ganimede® tanks?

A
  • can be fully automated
  • less labour intensive
  • specialised tanks are slightly more expensive than standard stainless steel tanks
44
Q

What is a Rotary fermenter?

A
  • horizontal, closed, stainless steel tanks
  • whole tank rotates
  • internal blades break up the cap to ensure adequate mixing
  • horizontal orientation of the tank increases the surface area between the grape skins and the juice
  • very extractive
45
Q

For what types of wines are Rotary fermenters used? Give examples.

A
  • high-volume, inexpensive or mid-priced wines that are acceptable or good in quality
  • red wines where medium to high levels of flavour, colour and tannin are desired
  • e.g. Cabernet Sauvignon- or Syrah-based wines
46
Q

What are the costs associated with Rotary fermenters?

A
  • can be programmed to rotate at certain times and for a certain amount of time
  • labour requirements are low
  • tanks are relatively expensive
47
Q

In addition to cap management techniques, what are two other methods of extraction?

A
  1. Must concentration

2. Co-fermentation

48
Q

What is must concentration? What is the French term?

A
  • aka ‘saignée’ (French)
  • levels of colour, flavours and tannins increased by drawing off some of the juice just after crushing and before the start of the ferment
49
Q

What are the disadvantages of must concentration?

A
  • lowers the volume of red wine that will be made from a set weight of grapes
50
Q

What is a side advantages of must concentration?

A
  • juice that is removed is typically light in colour, flavour and tannin and can be used to make rosé
51
Q

What is co-fermentation?

A
  • the process of fermenting different grape varieties together in the same vessel
  • commonly refers to the practice of fermenting a small proportion of white grapes (typically up to 5 per cent) within a red wine fermentation
52
Q

Why would a winemaker co-ferment white and red grapes together?

A
  • to take advantage of some of the phenolic compounds found in white grape varieties that increase colour intensity and stability through binding with anthocyanins (higher quality)
  • white grapes contribute aroma compounds (e.g. the terpenes in Viognier give floral and fruity characteristics)
53
Q

What is a risk of co-fermenting white and red grapes together?

A

Adding too much of the white grape variety can lead to dilution, and hence lower colour intensity

54
Q

Where did the technique of co-fermenting white and red grapes together originate? What grapes were co-fermented?

A
  • Rhone Valley

- Côte-Rôtie appellation was particularly famous for the co-fermentation of Syrah and Viognier

55
Q

What are the costs associated with co-fermentation?

A

Generally no additional costs

WsetDip D1 (87 decks)

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