18/18.1 Specific Options for Red Winemaking

Question 1

Comment on the main factors at play in red winemaking?

Answer 1

Most red wine options relate to the extraction of

anthocyanins, tannins and flavours from the grape skins

This is influenced by:

Temperature - the higher, the greater the extraction

Time on skin - and the more the skins are mixed through the juice (cap mgt) the more extraction takes place

Medium in which extraction takes place

• anthocyanins are soluble in water (grape must)
• tannins are soluble in alcohol.

Time and Medium are therefore very important in cap management and in fermentation

• at the start of the process - more anthocyanins are extracted
• at the end of the process as more alcohol has been produced - more tannins are extracted

Colour:

• Both anthocyanins and anthocyanin-tannin compounds change colour from ruby through to brown.
• However the LATTER more slowly
• o2 exposure via micro-oxygenation or barrel ageing facilitate the reaction between antho. and tannin to promote the colour stability.

Question 2

What is the ultimate aim in red winemaking?

Answer 2

• To extract just enough anthocyanins, tannin, and flavour so that the wine is suitably concentrated and balanced (care - not to extract too much)

Question 3

As single molecules, describe anthocyanins.

Answer 3

• 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)
• some o2 exposure is essential for the reaction between anthocyanins and tannins which promotes colour stability.

Question 4

Why are black grapes are less vulnerable to oxidation?

Answer 4

The phenolics found in the skins of black grapes have anti-oxidant properties

Question 5

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

Answer 5

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

Chilling is likely to be done if cold soaking is planned.