Level 4 D1 Chap 18 - Red Winemaking

Question 1

What compounds are sought in red wine over white, and what methods are used to obtain them over white winemaking?

Answer 1

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.

Question 2

What promotes colour stability?

Answer 2

Anthocyanins are the source of colour in young red wine.

These are more stable when bonded to tannins, normally through oxygenation.

Question 3

What options exist in red wine making processes, that are rarely or never used in white wine?

Answer 3

• mixing whole berries, or bunches, with crushed fruit for fermentation
• carbonic maceration
• semi carbonic maceration
• fermentation on skins
• cap management

Question 4

What maceration options are there in red winemaking and how do they differ?

Answer 4

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.

Question 5

Set out options and methods for maceration before fermentation

Answer 5

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

Question 6

What is the impact of pressing red wine before fermentation?

Answer 6

It may have colour instability and should be drunk young

The wine is typically inexpensive, low tannin, fruity style.

Question 7

What options reduce the impact of grey rot (botrytis) on still red wine?

Answer 7

Thermovinication or Flash Detente

Pre-fermentation maceration with heat can denature oxidative enzymes (laccase) in the fungus

Question 8

What causes a cap and how is it managed?

Answer 8

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

Question 9

How is punching down carried out?

Answer 9

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

Question 10

How is pumping over carried out?

Answer 10

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

Question 11

How is rack and return carried out?

Answer 11

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

Question 12

How does a Ganimede tank work?

Answer 12

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

Question 13

How do rotary fermenters function?

Answer 13

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

Question 14

What is co-fermentation?

Answer 14

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.

Question 15

What viniculture considerations are there for whole bunch fermentation?

Answer 15

Grapes need to be hand-harvested

Stems must be ripe

Question 16

What options are there for whole bunch fermentation and how do they differ?

Answer 16

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

Question 17

What chemical changes occur to grapes during whole bunch or whole berry fermentation?

Answer 17

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

Question 18

What temperature range may be used for red wine fermentation?

Answer 18

20°C for fruity, low tannins

30°C for concentration and tannin for increased age-ability

Question 19

What vessels are used for red wine fermentation?

Answer 19

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

Question 20

What are the considerations for post-fermentation maceration?

Answer 20

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

Question 21

What are the options when pressing red wine?

Answer 21

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

Question 22

What are the main options with MLC in red winemaking?

Answer 22

MLC is common in red wines.

Malolactic conversion can be encouraged:

• during fermentation
• after fermentation in tank
• after fermentation in barrels

Question 23

What winemaking processes or decisions can be made when maturing and finishing red wine for sale?

Answer 23

• blending
• use of oak
• lees ageing
• further blending
• stabilisation
• clarification
• packaging
  (NOTE: Same as white!)

Question 24

What lees ageing can be used in red wine production?

Answer 24

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.