Level 4 D1 Chap 18 - Red Winemaking Flashcards
What compounds are sought in red wine over white, and what methods are used to obtain them over white winemaking?
Anthocyanins, tannins and flavors from the grape skins
These are extracted through:
- higher temperatures (higher = more)
- longer time on skins (longer = more)
- matching extraction to the appropriate time (anthocyanins pre-fermentation, tannins during/after)
And cap management.
What promotes colour stability?
Anthocyanins are the source of colour in young red wine.
These are more stable when bonded to tannins, normally through oxygenation.
What options exist in red wine making processes, that are rarely or never used in white wine?
- mixing whole berries, or bunches, with crushed fruit for fermentation
- carbonic maceration
- semi carbonic maceration
- fermentation on skins
- cap management
What maceration options are there in red winemaking and how do they differ?
Maceration BEFORE fermentation to extract colour and flavour without tannin:
- cold soaking
- using heat
Maceration during fermentation also extracts tannins
Maceration after fermentation can further extract tannins and increase tannin polymerization.
Set out options and methods for maceration before fermentation
Cold soaking:
- juice and skins are held at 4°C - 10°C for 3-7 days.
- may use cap management during this (PD or PO).
E.g., used with Pinot Noir to maximise use of its low levels of anthocyanins and get more color
Thermovinification: heat the must to around 50°C - 60°C for minutes to hours
Flash détente:
- destemmed grapes heated to 85°C-90°C for a few minutes;
- rapidly cooled using vacuum.
- grape skin cells burst
In both heat processes, issues with color instability unless you ferment on skins
What is the impact of pressing red wine before fermentation?
It may have colour instability and should be drunk young
The wine is typically inexpensive, low tannin, fruity style.
What options reduce the impact of grey rot (botrytis) on still red wine?
Thermovinication or Flash Detente
Pre-fermentation maceration with heat can denature oxidative enzymes (laccase) in the fungus
What causes a cap and how is it managed?
Carbon dioxide bubbles cause the skins to float, forming a layer separated from the rest of the fermentation.
To maximise colour extraction, these can be circulated back into the wine by:
- Punching down
- Pumping over
- Rack and return
- Ganimede tanks
- Rotary fermenters
How is punching down carried out?
A hand or mechanical plunger submerges the cap.
If done by hand, then this requires a small, open top vessel and can only be done on premium wines - labor intensive
Gentle
How is pumping over carried out?
About 1/3 to 1/2 of the liquid in a fermentation vessel is pumped and sprayed over the top of the cap.
In an open tank this increases oxygen levels and reduces the risk of reductive flavours
Can be done anaerobically.
Very gentle
- combined with PD or R&R to extract enough color, flavor, tannin
How is rack and return carried out?
The liquid from the fermentation vessel is pumped into an empty vessel. This is then pumped back over the cap.
It is a highly effective extractive technique, so used only 1-3 times during fermentation
Requires labor to set up
How does a Ganimede tank work?
Ganimede tanks bubble up CO2 (or oxygen/air) through the wine. The cap bursts when the pressure is high enough
This is highly effective and less labour intensive than rack and return, although specialised tanks are required
How do rotary fermenters function?
The closed, horizontal stainless steel tanks rotate and internal blades break up the cap
These are very effective and have low labor costs, but imprecise, so used for larger volume mid-range reds
What is co-fermentation?
Co-fermentation is the process of fermenting different grape varieties together.
Most frequently up to 5% white grapes in a red wine fermentation. e.g. Syrah/Viognier in Côte-Rôtie
Take advantage of phenolic compounds in white that bind with anthocyanins to increase color stability.
White also contributes fruity aroma compounds.
What viniculture considerations are there for whole bunch fermentation?
Grapes need to be hand-harvested
Stems must be ripe
What options are there for whole bunch fermentation and how do they differ?
Carbonic maceration
- blankets whole bunches with added CO2.
- intracellular fermentation starts
- at 2% abv, grape skins split & release juice PLUS some grapes crushed by weight.
- grapes are pressed when alcohol reaches 2%
Beaujolais Nouveau
Semi-carbonic maceration
- load vessel with whole bunches
- bottom grapes are crushed grapes and release juice
- fermentation starts
- CO2 is generated & fills vessel
- intact grapes undergo carbonic maceration
This can be continued to develop to full fermentation
Used for fruity styles of many varieties
Whole berries with crushed fruit
- stems must be ripe
- whole berries are submerged under crushed fruit;
- that limits oxygen, and they undergo intracellular fermentation and are integrated and crushed during cap management
What chemical changes occur to grapes during whole bunch or whole berry fermentation?
The objective is to create an oxygen-free environment for the uncrushed fruit.
This causes the cells in the grape to switch from aerobic respiration to anaerobic metabolism.
This leads to intracellular fermentation (fermentation without yeast!).
Malic acid is broken down –> ethanol
Therefore, total acid is reduced, pH goes up
Glycerol levels increase, adding texture
Distinct aromas (kirsch, banana, bubble gum, cinnamon) emerge
Three forms of whole berry/bunch fermentation:
- Carbonic
- Semi-carbonic
- Whole bunch/berries with crushed fruit
What temperature range may be used for red wine fermentation?
20°C for fruity, low tannins
30°C for concentration and tannin for increased age-ability
What vessels are used for red wine fermentation?
Stainless steel, concrete and oak are all used.
Open top would be needed for punching down, but closed top can be used
Oak: normally large vats, but it is an option to ferment in barriques, with a small opening.
This is labour intensive and used for premium/ super-premium wines only
What are the considerations for post-fermentation maceration?
Post-fermentation maceration may be from a few days to a few weeks.
- thought to extract more tannins and also encourage polymerisation of tannins, increasing ageing potential.
Because of the time and tank space needed, it is used in premium/ super-premium wines
What are the options when pressing red wine?
Pressing may be carried out:
- just after cabonic maceration has happened, at 2% abv, to make fruity, low tannin wine
- before the end of fermentation, with a view to finish fermenting in barrel
- at the end of fermentation, or
- after post-fermentation maceration
Fermentation in barrels is thought to result in better integrated oak flavors and rounder mouthfeel
What are the main options with MLC in red winemaking?
MLC is common in red wines.
Malolactic conversion can be encouraged:
- during fermentation
- after fermentation in tank
- after fermentation in barrels
What winemaking processes or decisions can be made when maturing and finishing red wine for sale?
- blending
- use of oak
- lees ageing
- further blending
- stabilisation
- clarification
- packaging
(NOTE: Same as white!)
What lees ageing can be used in red wine production?
Lees ageing is not common in red wine production as it reduces colour intensity
Where it is used, it is normally fine lees, with no stirring.
