D1.C18. Specific Options for RedWine Making Flashcards
1
Q
Many of the choices involved in red winemaking are focused on:
A
The extraction of anthocyanins, tannins and flavours from the grape skins
2
Q
What is the general aim in red wine making?
A
To extract anthocyanins, tannins and flavours so that the wine is suitably concentrated and balanced, but not to extract too much
3
Q
What are the factors that affect the extraction of anthocyanins, tannins and flavours?
A
- Temperature
- Time on skins
- The medium in which the extraction is taking place (tannins are more soluble in alcohol, anthocyanins in water)
4
Q
Which processes in winification can lead to the alteration or loss of anthocyanin molecules?
A
- Lees aging
- Additions of SO2
5
Q
Which interactions make anthocyanins more stable?
A
- Binding with the tannins
- Gentle oxidation of wine (micro-oxygenation, barrel aging)
6
Q
What is the result of change in the composition of anthocyanins and anthocyanin - tannin compounds over time?
A
Wine becomes paler and gradually changes from ruby through to brown. However, this change is slower for anthocyanin-tannin compounds than anthocyanins
7
Q
Is chilling the grapes in the winery needed for black grapes?
A
Although the phenolics found in the skins of black grapes make them less vulnerable to oxidation than white grapes, chilling still helps to slow down oxidation, as well as reducing the threat from spoilage organisms. Grapes may also be chilled now if cold soaking is planned
8
Q
What is the key aim of maceration before fermentation?
A
To extract colour and flavours, without extracting tannins
9
Q
What is the temperature range for cold soaking? Why?
A
- 4–10°C
- To reduce the rate of oxidation, the threat from spoilage organisms and the risk of a spontaneous fermentation starting
10
Q
What is the duration of cold soaking for red wines?
A
3-7 days
11
Q
What are the benefits of cap management techniques like punching down and/or pumping over during cold soaking?
A
- Aids extraction of flavours and colour
- To avoid the growth of spoilage organisms that need oxygen, such as acetic acid bacteria, on the top of the cap of skins
12
Q
Why is cold soaking suitable for premium wines?
A
- It is gentle technique. Cold temperatures result in a slow extraction, which can easily be monitored and controlled to achieve the level of extraction desired
- There is a cost to cold soaking in the energy required to chill the wine and also, time taken for cold soaking (tying up valuable tank space)
13
Q
Cold soaking is commonly used for which black grape variety? Why?
A
- Pinot Noir
- To promote colour intensity
14
Q
What are the two techniques used for macerations using heat?
A
- Thermovinification
- Flash détente
15
Q
How is thermovinification performed?
A
- The must is heated to around 50–60°C and sometimes higher
- The time spent macerating at this heat can range from a number of minutes to several hours (higher the temperature, shorter the maceration)
16
Q
How is flash détente performed?
A
- Destemmed grapes are quickly heated to 85–90°C
and then rapidly cooled under a vacuum - This takes place in as little as two minutes
- The process bursts the cells in the grape skins allowing a very rapid extraction of anthocyanins and flavours
- The short time at high temperatures limits the risk of ‘cooked’ flavours developing
17
Q
Why is flash détente used in high-volume wineries?
A
Because the vacuum system is expensive to buy
18
Q
After performing macerations using heat, what are the options?
A
- The juice may be pressed off the skins before fermentation to produce a low tannin, fruity style wine or may be blended with higher quality wines bringing juicy, fruity flavours
- The juice may be fermented for a period of time on the skins if a style with more tannin is required.
19
Q
What is the disadvantage of pressing of the skins before fermentation when maceration using heat is performed?
A
- Wines tend to have colour instability because there is not enough tannin to bind with the anthocyanins and form more stable compounds
20
Q
What are the other benefits of using thermovinification and flash détente?
A
- Both flash détente and thermovinification 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
21
Q
What are the benefits of cap management techniques?
A
- Without mixing, the skins spend the fermentation macerating in the same small volume of liquid that surrounds them
- Avoiding a dry cap, which can harbor acetic acid bacteria
- Avoiding the production of reductive sulphur compounds by aerating the must
- It also helps to distribute the heat produced during fermentation and is therefore essential for temperature monitoring and control
22
Q
What are the main choices for cap management?
A
- Technique/techniques to be used
- Frequency and duration of the technique/techniques of mixing
- Timing of mixing (more mixing at the start of
fermentation with less mixing at the end will extract more colour and less tannin)
23
Q
What is the role of temperature on the extent of extraction by cap management?
A
Warmer fermentations will extract more than cooler fermentations
24
Q
How can tannin extraction be reduced near the end of fermentation?
A
By cooling the wine
25
What are the ways to perform punching down (pigeage)?
- By hand
- By mechanised plunger
26
Why carrying out punching down procedure by hand is best suited to low-volume production of premium wines?
- Carrying out this procedure by hand is labour intensive
- It is only physically possible to punch down the cap
manually and ensure adequate mixing of the skins in relatively small, open top vessels. Small vessels mean more labour for monitoring
27
How is pumping over (remontage) performed?
Juice/wine is taken from near the bottom of the vessel and sprayed over the cap of skins. Usually around one-third to one-half of the liquid in the vessel is pumped and sprayed over
28
Why is punching down and rack and return techniques are also performed together with pumping over?
Because pumping over is a more gentle technique that sprays the liquid over the cap, rather than breaking up the cap, so punching down and rack and return is needed to extract enough colour, flavour and tannin
29
What are the advantages of pumping over?
- It can be carried out aerobically, by splashing the wine against the inside wall of the open vat, which can be beneficial for yeast health and avoidance of reductive off-flavours
- Modern wineries have pumps and hoses installed at each tank, and pump-overs can be pre-programmed to occur at certain times and for certain durations, reducing the need for labour
30
How is rack and return (delestage) performed?
- As the juice is pumped from one vessel into another vessel, the cap of skins falls down the vessel
- The juice is then pumped from the new vessel in through the top of the original vessel and is sprayed over the skins, which breaks up the cap and mixes the juice and
skins thoroughly
31
Why rack and return may be used only 1–3 times during the fermentation?
Because it is more extractive than pumping over or punching down
32
Rack and return is most commonly used for producing which style of wines?
For red wines where medium to high levels of flavour, colour and tannin are desired (e.g. Cabernet Sauvignon, Syrah)
33
What are the disadvantages of rack and return?
- It cannot be fully automated and requires labour to set up and monitor the process
- It requires a clean vessel to be available, which can be an issue in wineries that are operating at peak capacity
34
What are Ganimede® tanks?
- They are specialised tanks that bubble CO2 up through the must/wine
- Pressure builds up under the cap, until finally the cap burst
- It is relatively extractive technique like delestage
35
Why are Ganimede® tanks becoming increasingly common?
- Because it can be fully automated
- Oxygen can be used instead of CO2 if the winemaker wants or needs to expose the wine to oxygen
36
What is the disadvantage of Ganimede® tanks?
These specialised tanks are slightly more expensive than standard stainless steel tanks
37
What are the advantages of rotary fermenters?
- The horizontal orientation of the tank increases the surface area between the grape skins and the juice
- The tank can be programmed to rotate at certain times and for a certain amount of time, so labour requirements are low
38
Why are rotary fermenters best suited to the
production of wines with medium to high levels of colour, tannin and flavour intensity, such as Cabernet Sauvignon- or Syrah-based wines?
Because they are very effective at extracting
39
Why are the rotary fermenters commonly used for high-volume, inexpensive or mid-priced wines that are acceptable or good in quality?
- Techniques that are gentler or allow a bit more precision are usually preferred for very good to outstanding, premium-priced wines
- They are expensive so large volumes of wine need to be fermented in them to make them cost effective
40
What is an alternative way to increase colour, flavours and tannins?
Concentrating the must by drawing off some juice just after crushing, before thr fermentation starts
41
What is the effect of must concentration on the price of the wine?
Since it lowers the volume of the wine, the price is increased
42
How can the juice drawn off to concentrate the must, be used?
It can be used to produce rosé wines (saignée method)
43
What is the typical amount of white grapes that are co-fermented with black grapes?
Up to 5 %
44
What are the advantages of co-fermentation?
- Phenolic compounds found in white grape varieties that can increase colour intensity and stability through binding with anthocyanins
- White grapes can also contribute aroma compounds (e.g. the terpenes in Viognier give floral and fruity characteristics)
- It does not incur any particular costs
45
What can be the risk of co-fermentation?
Adding too much of the white grape variety can lead to dilution and hence lower colour intensity
46
What is the origin of co-fermentation technique?
Cote Rotie appellation
47
What are the prerequisites of whole berry/bunch fermentation?
- Grapes must be hand harvested
- Stems of the bunches should be fully ripe
48
What is the effect of the stems on flavour profile in whole bunch fermentations?
Stems can add flavours that are sometimes described as ‘spicy’ or ‘herbal’ and can also add some tannins
49
How can the stems be used to provide tannins and spicy flavours in crushed fruit fermentations?
Winemakers can add stems (left over from the destemming process) to crushed fruit fermentations
50
For which kinds of varieties, adding stems to crushed fruit fermentations is not common?
Varieties with naturally high tannins, such as Cabernet Sauvignon
51
What is the objective of whole berry/bunch fermentations?
To create an oxygen-free environment for the uncrushed fruit
52
What are the outcomes of oxygen-free environment for the uncrushed fruit?
- The grapes change from aerobic respiration to anaerobic metabolism
- Some of the sugar in the grapes is converted to alcohol without involvement of ant yeast (intracellular fermentation)
- Malic acid within the grape is also broken down to create ethanol, which can reduce the malic acid by upto 50 %
- Glycerol levels increase, which can add texture
- A range of distinctive aromas is created inside the grape, commonly including kirsch, banana, bubble gum and cinnamon
53
What are the three forms of whole berry/bunch fermentation?
- Carbonic maceration
- Semi carbonic maceration
- Whole berries/bunches with crushed fruit
54
How is carbonic maceration performed?
- Whole, uncrushed bunches are placed into vessels that are filled with CO2
- Intracellular fermentation starts, producing about two per cent alcohol by volume
- At this point, either the grapes are crushed in the normal
way or the grape skins start to split and the grapes release their juice
- Normal fermentation commences
- The juice is generally drained immediately (no further maceration on the skins)
- The free run juice and press juice are typically blended
- Yeast then complete the fermentation off the skins
55
Why does carbonic maceration extracts colour from the grapes, but little tannin?
Because tannin is most easily extracted in the presence of alcohol) and alcohol is only around 2 per cent
56
What are the characteristics of wines produced by carbonic maceration?
- They typically have low tannins with distinctive notes from intracellular fermentation, alongside the fruit notes from the grape variety.
- Flavours created are distinct, but not especially complex
57
Are the wines produced by carbonic maceration usually oaked?
No, flavours of oak are usually not a desirable addition to the fruity, candy-like flavours of these wines
58
Do the wines produced by carbonic maceration have aging potential?
No, they are best consumed within a year after harvest
59
What is the difference between semi-carbonic maceration and carbonic maceration?
- Semi-carbonic maceration, does not involve filling the vessel with CO2
- The grapes at the bottom of the vessel are crushed under the weight of the grapes above and some juice is released
- Ambient yeast start to ferment the juice (cultured yeast can also be added). This fermentation produces CO2, which fills the vessel and the remaining intact grapes undergo carbonic maceration
60
What can the winemaker do if he wants to produce a wine with a slightly more concentration, body and tannin (hence a longer aging capacity) for the wines produced by semi-carbonic maceration?
- Alcoholic fermentation may continue on the skins and involve some punching down or pumping over
- The alcoholic fermentation may be followed by a post- fermentation maceration and/or maturation in oak
61
What is the advantages semi-carbonic maceration?
- This approach can lead to a better integration of the aromas from intracellular fermentation with aromas from the grape variety
- It results in wines with more fruitiness and a softer mouthfeel than crushed fruit fermentations
62
Which varieties can be used for semi-carbonic maceration to produce fruity styles?
Pinot Noir, Malbec, Tempranillo, Gamay and Carignan, among other grape varieties
63
How is oxygen-free environment obtained in whole berries/bunches with crushed fruit technique?
Whole berries/bunches are largely submerged in crushed fruit
64
How can carbonic characteristics be increased in whole berries/bunches with crushed fruit technique?
By raising the percentage of whole berries/bunches
65
What are the effects of using whole berries/bunches with crushed fruit on the taste of wine?
It is generally thought to give a smoother texture and more vibrant and fresh primary aromas (than crushed fruit fermentations)
66
Why do the winemakers wanting to produce fruity, low tannin wines will typically ferment at relatively cool temperatures (e.g. 20°C)?
Warm temperatures can cause volatile, fruity aromas to evaporate,
67
The temperature which is ideal to produce wines with the concentration and tannin structure to age is:
Warmer temperatures (e.g. 30°C)
68
What kinds of vessels can be used for the fermentation of red wines?
- Stainless steel, concrete or wooden
- Open top (needed for extraction techniques) or closed
69
What types of oak barrels can be used for the fermentation of red grapes?
It is generally in the form of a large vat; however, small oak barrels (e.g. 225–500 L) are sometimes used
70
Why is fermentation in oak barrels suitable for premium and super-premium priced wines?
Managing fermentations in these vessels is extremely labour intensive
71
What are the advantages of fermentation in oak vessels?
- It gives a rounder mouthfeel to the wine
- It leads to better integration of oak compounds during maturation
72
What is the advantage of fermentation in concrete and stainless steel vessels?
Concrete and stainless steel help to retain fruit flavours
73
What is the duration of post-fermentation maceration, if practiced?
From a few days to a few weeks
74
What is the aim of post-fermentation maceration?
- To further extract tannins
- To encourage the polymerisation of tannins, with the aim of improving tannin structure and texture and the wine’s ageing potential
75
Why is post-fermentation maceration generally conducted on premium and super-premium, very good and outstanding wines?
Post-fermentation maceration also takes up tank space and time so it is not possible or desirable from a logistical point of view in the production of high-volume, inexpensive wines
76
Is flushing the machines with inert gas are less widely practiced during pressing of red wines?
No, red wine is usually better protected against the
effects of oxidation than white wine
77
What are the characteristics of free run wine when compared with press wine?
The free run wine contributes fruity flavours and is lower in tannins than the press wine.
78
What are the two parameters that determine the quality of the press wine?
- Quality of the fruit
- Management of the press
79
What is the effect of high quality grapes and gentle first pressings on the wine?
They enhance the tannin structure of a wine
80
What is the effects of lesser quality grapes and rougher pressing on the wine?
They can increase bitterness
81
What is the main factor which determines the timing of pressing in red wines?
Style of the wine
82
What are the options for timing of pressing in red wines?
- When the fermenting must reaches 2% abv, for the wines produced with carbonic maceration
- Straight after alcoholic fermentation is complete
- After a period of post-fermentation maceration to maximise the tannin structure of the wine
- Just before the end of alcoholic fermentation, usually with the intention that the wine will finish fermenting in barrels (Thought to lead to a better integration of oak flavours and rounder mouthfeel)
83
What are the options that the winemakers have, for the malolactic conversion of red wines?
- Vessel: Oak, stainless steel or concrete
- Timing: During or after alcoholic fermentation
84
Which vessels are preferred for malolactic conversion of red wines?
Oak barrels. It can lead to a better integration of oak characteristics during maturation
85
What is the effect of malolactic conversion on the acidity of the wine?
It decreases the acidity and increase the pH of the wine. It is possible to adjust the acidity of the wine as necessary
86
What are the common practices for inexpensive red wines in terms of maturation in wooden vessels?
- They do not generally undergo maturation in barrel
- Oak alternatives such as staves, which can be inserted into a stainless steel tank or concrete vat and can provide oak flavours cheaply and quickly
87
What are the common practices for mid-priced, premium and super-premium red wines in terms of maturation in wooden vessels?
The majority of mid-market, premium and super-premium
red wines will be matured in oak vessels for a range of time (6 months to two years)
88
When do the winemakers choose not to mature the wines in oak or to mature them in old oak for a short period for mid-priced, premium and super-premium red wines?
When the winemaker wants the focus to be on the primary
aromas and flavours of wines (Unoaked styles of Loire Valley Cabernet Franc, Spanish Mencía and Argentine Malbec)
89
What are the effects of maturation in oak vessels on the wine?
- It enhances the complexity of the wine by adding flavours of oak (vanilla, cloves, etc.), if new oak is used
- Gentle oxidation, particularly in small oak vessels
- Helps to soften tannins and can lead to the development
of tertiary aromas and flavours that can enhance complexity and quality
.
90
What are the advantages and disadvantages of lees aging for red wines?
- Advantage: Can help soft tannins
- Disadvantage: It can reduce the colour intensity
