Red: Crushed Fruit Fermentation

Question 1

What are the two categories of maceration prior to fermentation?

Answer 1

1. cold soaking
2. macerations using heat

Question 2

Define “cold soak”.

Answer 2

• to macerate the grapes at low temps in order to extract color and flavor while avoiding fermentation, spoilage, and oxidation

Question 3

What does the process of cold soak involve?

Answer 3

• cooling the crushed grapes to around 4-10C
• punching down or pumping over
• 3-7 days of maceration before raising the temp to initiate fermentation

Question 4

What styles of wine might use a cold soak?

Answer 4

• premium made from thin-skinned grapes such as Pinot Noir, where color extraction is required

Question 5

Why is cold soak not used on high volume, inexpensive wines?

Answer 5

• there are costs associated with the cooling and storage time, tying up valuable tank space

Question 6

What are the advantages of cold soak?

Answer 6

• careful extraction of color and flavor, which can be monitored and controlled to achieve the level of extraction required

Question 7

What are the two most common ways of maceration using heat?

Answer 7

1. flash detente
2. thermovinification

Question 8

Define flash detente.

Answer 8

• a heat-based maceration technique where grapes are heated to 85-90C, and then rapidly cooled under vacuum

Question 9

How does flash detente speed up extraction?

Answer 9

• bursts the cells in the skins of the grapes, allowing for rapid extraction of anthocyanins and flavor
• the short time at high temps reduces the risk of cooked flavors

Question 10

What are the disadvantages of flash detente?

Answer 10

• equipment is expensive, and is restricted to high volume wineries where throughput justifies the cost
• resulting wines may have poor color stability, due to the lack of tannins extracted, and so is suited to wines that should be drunk young

Question 11

Define thermovinification.

Answer 11

• heated maceration technique where the must is heated to 50-60C for a few minutes to several hours

Question 12

What are the advantages of flash detente and thermovinification?

Answer 12

• speeds up winemaking process
• beneficial for grapes that are affected by grey rot, as it denatures the enzyme Laccase
• both techniques can increase the fruitiness of the wines
• flash detente can reduce smoke taint

Question 13

Name 5 methods of cap management.

Answer 13

1. punching down (pigeage)
2. pumping over (remontage)
3. rack and return (delestage)
4. ganimede tanks
5. rotary fermenters

Question 14

Why is cap management important when macerating during fermentation?

Answer 14

• grape skins rise above the level of the liquid due to CO2 generation
• avoids saturation of the must in contact with the skins
• avoid acetic acid bacterial contamination of the skins
• aids aeration of the must to avoid the production of reductive compounds
• distributes the heat produced during fermentation

Question 15

What four variables of cap management can affect the extraction?

Answer 15

• cap management technique
• cap management frequency and duration
• timing of cap management within the period of fermentation
• temperature of fermentation

Question 16

Define punching down.

Answer 16

• using a handheld or automated plunger to submerge the cap into the liquid below

Question 17

What are the disadvantages of punching down?

Answer 17

• labor intensive, and therefore expensive
• requires small, open-topped vessels, so is usually only used on small volumes of premium wines

Question 18

What are the advantages of punching down?

Answer 18

A gentle process that avoids over-extraction

Question 19

Define pumping over.

Answer 19

• a method of cap management where fermenting juice is take from the bottom of the vessel and sprayed over the cap

Question 20

What are the advantages of pumping over?

Answer 20

• very gentle technique
• can be carried out anaerobically or aerobically, in which case it can help oxygenate the must
• can be carried out in large or small vessels
• can be automated to not require manual operations, and can take place regularly throughout the day and night

Question 21

Define rack and return.

Answer 21

• cap management technique where the wine is pumped from the fermentation vessel into another vessel, and then pumped back over the cap of the original vessel

Question 22

What are the advantages and disadvantages of rack and return?

Answer 22

Advantages:

• very effective at breaking up the cap, and mixing the juices and skins thoroughly
• very extractive
• can be used to remove seeds from the fermentation by leaving them behind from the racking tank

Disadvantages:

• requires a spare tank
• requires labor to set up and monitor
• cannot be fully automated

Question 23

What are Ganimede tanks?

Answer 23

• specialized tanks that use the CO2 created during fermentation to disrupt and mix the cap

Question 24

What are advantages and disadvantages of using the Ganimede system?

Answer 24

Advantages:

• can be fully automated
• oxygen can be used, instead of CO2 if oxygen exposure is required
• extractive technique that is suited to producing wines with high levels of color tannin and intensity

Disadvantages:

• more expensive than standard tanks

Question 25

What are rotary fermenters?

Answer 25

• horizontal, closed SS tanks
• rotate, and internal blades break up the cap and ensure adequate mixing

Question 26

What are the advantages and disadvantages of rotary fermenters?

Answer 26

Advantages:

• very effective at extracting
• automated and can be programmed with sequences of rotation
• low labor requirements

Disadvantages:
- can be expensive
- imprecise, so might not be suitable for premium wines

Question 27

What other maceration options does a winemaker have?

Answer 27

• must concentration
• co-fermentation

Question 28

Define must concentration.

Answer 28

• increasing the levels of tannins, color, and flavors of a wine by drawing off some of the juice after crushing grapes to concentrate the remaining must

Question 29

What are the considerations related to must concentration?

Answer 29

• lowers the volume of the resulting red wine, increasing cost
• the drawn-off juice can be used to make Rose, known as Saignee in French

Question 30

What is co-fermentation?

Answer 30

• the process of fermenting different varieties together in the same vessel
• typically the practice of fermenting a small proportion of white grapes within a red wine fermentation

Question 31

Why would a producer choose to co-ferment white grapes with their red grapes?

Answer 31

• reported to take advantage of the phenolic compounds in order to stabilize color intensity and stability
• white grapes can also provide aroma compounds
• research results are mixed