Ch 7 - Oak And Inert Vessels

Question 1

How does oak maturation influence wine style?

Answer 1

As oak allows a small level of oxidation tannins can soften (red wine), tertiary flavours can develop and colour can change. In addition oak will have SPECIFIC additional impacts:
* oak tannins can be extracted giving structure/mouthfeel to both red and white wines;
* oak can give aromas and flavours of vanilla, smoke and cloves, sweet spices, toast.

Question 2

Why is hygiene an issue with oak barrels?

Answer 2

It is difficult to keep wooden barrels free of yeasts, bacteria and moulds, which can ruin the wine.

Question 3

What are the four important factors for winemakers to consider in choosing oak vessels?

Answer 3

• Species and origin of oak;
• size;
• production process;
• age.

Question 4

Why is species and origin relevant?

Answer 4

Characteristics and the aromas and flavours they impart are different by species and within species depending on origin eg Europe or America.

Question 5

What effect does barrel size have on the wine?

Answer 5

Smaller barrels (225 litre) have more wood in contact with surface of the wine than larger (2000 litre) barrels, so have a greater effect on the wine.

Question 6

How does production affect the barrel and the influence on the wine?

Answer 6

As the wooden staves used to make the barrels are heated, this transforms the tannins and flavour compounds in the oak, giving notes of sweet spice and toast. The length of time of heat exposure and temperature ( toasting) affect the flavours the barrel contributes to the wine.

Question 7

What happens as barrels are used?

Answer 7

The effect of toasting diminishes as it is used (aged). By fourth use there is little flavour or tannin imparted to the wine. The choice between old and new barrels will affect the style and taste of the wine.

Question 8

What alternatives are used to oak barrels?

Answer 8

• As barrels can be very expensive winemakers may use oak staves or chips which can be added to fermentation or maturation in inert vessels. Both provide some oak aromas and tannins at low cost;

Question 9

What is meant by inert vessels?

Answer 9

Inert vessels do not add any flavour to wine or allow oxidation. Normally stainless steel or concrete used for fermentation and storage.

Question 10

What are advantages of stainless steel vessels?

Answer 10

Easy to keep clean, can be made in any shape or size and have in-built temperature control.

Question 11

Describe a concrete vessel. Are the any disadvantages to their use?

Answer 11

Usually made from cement lined with epoxy resin which is inert and waterproof.
Less easy to clean and maintain. Mainly replaced by stainless steel tanks.
Still favoured by some winemakers.