18/18.1 Specific Options for Red Winemaking

Question 1

What are the main factors at play in red winemaking?

Answer 1

• The extraction of anthocyanins, tannins and flavours from the grape skins

Question 2

What is the ultimate aim in red winemaking?

Answer 2

• To extract these compounds so that the wine is suitably concentrated and balanced, but not to extract too much

Question 3

What are the 4 main factors that affect extraction from red grapes?

Answer 3

1. temperature – higher temperatures result in greater extraction
2. time on skins – generally, the longer the juice/wine remains in contact with the skins the greater the extraction
3. management of the skins and juice – the more the skins are mixed through the juice, the greater the extraction
4. medium in which the extraction is taking place – for example, tannins are most soluble in alcoholic solutions (e.g. wine), whereas anthocyanins are most soluble in aqueous solutions (e.g. grape must)

Question 4

What provides a source of color in young red wines?

Answer 4

Anthocyanins

Question 5

As single molecules, describe anthocyanins.

Answer 5

• as single molecules they are not very stable

- colour can be altered or lost in the process of different winemaking procedures (lees ageing, additions of SO2)

Question 6

How do anthocyanins become more stable? What facilitates this?

Answer 6

• When they combine with tannins, resulting in greater colour stability
• Oxygen facilitates this reaction

Question 7

Why does gentle oxygenation of the wine promote colour stability?

Answer 7

• Oxygen facilitates reaction with tannins and anthocyanins to make the colour more stable

Question 8

Give 2 examples of gentle oxygenation that may take place in red winemaking.

Answer 8

• micro-oxygenation and barrel ageing

Question 9

Overtime, how do anthocyanins and anthocyanin-tannin compounds affect the wine? Which is slower to take effect?

Answer 9

• change in composition over time and the wine becomes paler and gradually changes from ruby through to brown
• change is slower for anthocyanin-tannin compounds than anthocyanins (which is why oxygentation is good)

Question 10

What grapes are less vulnerable to oxidation?

Answer 10

Black grapes

Question 11

Why are black grapes are less vulnerable to oxidation?

Answer 11

The phenolics found in the skins of black grapes

Question 12

When transporting black grapes to the winery, what is beneficial?

Answer 12

Chilling still helps to slow down oxidation, as well as microbial spoilage