D1C18 Red Winemaking

Question 1

What are 4 factors that affect extraction of tannins, anthocyanin and flavours from grape skins?

Answer 1

1) temperatures (higher = greater extraction)
2) time on skins (longer = greater extraction)
3) management of skins and juice (more mixing = greater extraction)
4) medium in which extraction is taking place (tannins more soluble in alcoholic solutions, anthocyanin more subtle in aqueous solutions)

Question 2

What is the key of maceration before fermentation in red wines and what are two ways to do it?

Answer 2

• key is to extract colours and flavours without extracting tannins
• tannins are not readily extracted at this point because they’re more soluble in alcoholic liquids
  1) cold soaking
  2) macerations using heat (flash detente and thermovinification)

Question 3

What is the process of cold soaking?

Answer 3

• juice and skins chilled to around 4-10 C to reduce oxidation, microbial spoilage and spontaneous fermentation
• usually lasts 3-7 days with use of punching down/pumping over
• gentle technique, suitable for premium wines
• commonly used on PN

Question 4

What is the process of flash detente?

Answer 4

• de-stemmed grapes are quickly heated to 85-90C then rapidly cooled under a vacuum (takes 2 minutes)
• the process bursts the cells in grape skins, allowing very rapid extraction of anthocyanin and flavours
• can be used for smoke taint

Question 5

What is the process of thermovinification?

Answer 5

• a form of maceration before fermentation that involves heating the must up to 50-60C to extract flavours and colours from red grapes

Question 6

What is punching down?

Answer 6

Plunger is used to submerge cap of grape skins in liquid (done by hand or machine)

Question 7

What is pigeage?

Answer 7

Hand punching down in small, open-top vessels

Question 8

What is pumping over?

Answer 8

• wine/juice is then from bottom of vessel and sprayed over cap of skins
• very gentle, can be carried out aerobically or anaerobically
• used in black varieties for wines of all price points

Question 9

What is rack and return?

Answer 9

• similar to pumping over, but juice is pumped from one vessel to another vessel
• it is then sprayed back into original vessel on top of now broken cap and mixes skin thoroughly
• more extractive so may only be used 1-3 times per fermentation alongside other methods
• commonly used for red wines where medium-high levels of flavour, colour and tannin are desired

Question 10

What are Ganimede tanks?

Answer 10

• specialized tanks that bubble CO2 or oxygen up through must/wine, building pressure under cap until it bursts
• breaks up cap so relatively extractive
• new technique becoming common because can be automated but it’s expensive

Question 11

What are rotary fermenters?

Answer 11

• horizontal, closed, stainless steel tanks that rotate and internal blades break up cap
• commonly used in high-volume, inexpensive wines

Question 12

What are 2 less common maceration options during fermentation?

Answer 12

1) must concentration (saignee)
- increase levels of colour, flavour and tannins by drawing off some juice after crushing/at the start of ferment
- lowers volume but removed juice makes rose
2) co-fermentation
- commonly refers to fermenting a portion white grapes (up to 5%) within a red wine fermentation
- Cote Rotie famous for Syrah and Viognier

Question 13

What is the objective of whole berry/bunch fermentations in red wines?

Answer 13

To create an oxygen-free environment for uncrushed fruit

Question 14

What is intracellular fermentation?

Answer 14

• grapes change from aerobic respiration to anaerobic metabolism where some of the sugar in the grapes is converted to alcohol without the involvement of any yeast
• glycerol levels increase (adding texture) and a range of distinctive aromas (kirsch, banana, bubblegum)

Question 15

What is carbonic maceration?

Answer 15

• involves planting only whole, uncrushed bunches into vessels that are then filled with CO2 to remove oxygen
• intracellular fermentation starts
• once level of alcohol in grape reaches 2%, grape skins split and release juice
• yeast then complete fermentation off skins
• method extracts colour but little tannin
• ex. Beajolais Nouveau

Question 16

What is semi-carbonic maceration?

Answer 16

• doesn’t involve filling vessel with CO2
• vessel is filled with whole bunches, the grapes at thee bottom are crushed under weight of grapes above and some juice is released
• ambient yeast starts fermentation
• fermentation produces CO2 which fills vessels and remaining intact grapes undergo carbonic maceration
• produces wines with slightly more concentration, body, tannin and aging capacity (fruiter Malbec, PN, Gamay, etc.)

Question 17

What is the process of fermenting whole berry/bunches with crushed fruit?

Answer 17

• although whole berries/bunches are not blanketed in CO2, they are largely submerged by the crushed grapes and kept away from oxygen therefore intracellular fermentation happens
• thought to give smoother texture and more vibrant/fresh primary aromas

Question 18

What are fermentation temperatures for red wines?

Answer 18

• 20C for fruity, low tannin wines

- 30C for greater extraction/tannin/structure/ability to age

Question 19

What are fermentation vessels for red wines?

Answer 19

• stainless steel and concrete retain fruit flavours

- oak (usually large vat) gives rounder mouthfeel and leads to better integration of compounds during maturation

Question 20

When does pressing happen in red wines?

Answer 20

• when no more extraction is desired

- timing is variable – depends on style being produced

Question 21

What can lees aging do for red wines?

Answer 21

• can help soften tannins but reduces colour intensity
• not typical to keep gross lees nor stir lees
• racking can be used to separate wine from lees therefore control amount of lees present