D1 Maturation, Lees, Blending Flashcards
The role of oxygen in Maturation
Oxidation leads to :
1. a reduction in primary aromas and development of tertiary aromas (dried fruits and nuts)
2. Influence colour:
- white wines colour become darker, gold then brown.
- red wines colour become more stable due to the anthocyanin binding with tannins, (protecting the colour from being bleached by SO2 addition or lees)
3. Soften tannins (linked to anthocyanin and tannins bonding)
Maturation can last 6-12 months in white wines and 12-24 months in red wines ((due to higher anti-oxidative phenolics (tannins)).
Wooden vessels
Wooden vessels allows a slow, gradual exposure to oxygen through the pores and the gaps between the staves of the vessels.
Also, wine is in contact with oxygen during racking, lees stirring or topping up.
Wine is lost during maturation in wood as water and alcohol impregnate the wood and also evaporates.
The smaller the vessel the higher the rate at which the wine is lost, meaning the barrels needs to be topped up more frequently, leading to more oxygen exposure.
Micro-Oxygenation
Micro-oxygenation provide a cheaper alternative.
Oxygen is bubbled through the wine
(dosed in units of mg/L per month).
Generally carried out in stainless steel tanks.
This increase colour stability, soften tannins, improve texture and and reduce unripe and herbaceous flavours.
Also, if used with oak alternatives can help integrate oak flavours.
This method save costs of the wooden barrels and allows a controlled rate of oxygen exposure.
However, because of the increased level of oxygen, it can favour spoilage organisms such as acetic acid bacteria and Brettanomyces.
Temperature and Humidity
Temperature and humidity control systems are common.
White wine 8-12C, red wines 12-16C.
Cool temperatures slows down the rate of oxidation and reduce threat from spoilage organism.
Warm temperature also increase the rate of wine loss, reducing the volume of wine to sell. Barrels needs more topping up, increasing risk of excessive oxidation and increasing labour costs.
Humidity must be not below 70%. Low humidity cause water loss to be quicker than alcohol and can lead to an excessive higher alcohol concentration.
The Role of wood in maturation
The influence of wood depend on:
- The age of the vessel
New wood impart more oak flavour than used wood. (a barrel loses 50% of its new oak flavour every year) - the size of the vessel
Barriques (225 l) holds small volume of liquid compare to the surface area. Therefore there is a greater benefit from the wood than in Foudres (more than 1000 l) - the type of wood
Oak have different characteristics, depending of where it is grown.
- European oak (French, Hungarian, Russian, Slavonian):
Contributes delicate aroma of vanilla, more tannins.
Price 600-1200 Euros. Pricier because the oak must be split to create staves and because grows slower.
- American oak:
Contributes intenser aroma of coconut, less tannins.
Price 300-600 Euros. Cheaper because oak can be sawn to create staves (more vessels can be made with the same amount of wood) and because grows quicker.
The slower the oak tree grows, the tighter the grain of the wood are, resulting in slower extraction of compounds and tannins.
Chestnut, cherry and acacia are occasionally used.
- the production of the vessel
The wood is seasoned (outside for 2-3 years) to lower humidity, reduce bitter flavour and increase aroma compounds (vanilla, clove).
Then toasted (can be light, medium, heavy). Contributes to other aroma compounds (spice, caramel, nuts, char, smoke).
Cost of Maturation in wood
Barrels are expensive to buy.
If Barriques are used, a lot of them may be needed adding cost of monitoring each barrel and winemaking operation (racking, lees ageing) is labour intensity.
Barrel maturation is a slow process (1-2 years) and therefore requires time and storage, meaning return of investment is slow.
Oak alternatives
For inexpensive and mid-priced wines alternative to oak include oak chips and oak staves (can be attached inside the stainless steel or concrete vessel, or they can float in the wine.
Micro-oxygenation can be used to give the gentle oxidation of barrel maturation to integrate the oak flavours.
This is cheaper than purchasing a barrel.
Also, can be done in a large tank, therefore is less labour intensive.
The role of lees ageing
Lees is made up of dead yeast.
(grape fragments, precipitated tannins, nutrients).
There are :
- Gross lees (larger, heavier particles).
- Fine lees (fine lees).
Lees are removed by racking, transferring wine from one vessel to another through a hose.
It is a n oxidative process, therefore may be carried out to increase oxygen exposure.
The wine may age on the lees.
The yeast cells break down (autolysis) releasing compounds that contributes flavour (yoghurt, dough, biscuit, toasted bread), body and texture.
Some of this compound bind with phenolic (tannins) reducing colour and softening tannins.
This process of stirring the lees in known as Batonnage.
Lees protect the wine from oxygen, help maintaining a slow, controlled oxidation. However, if in excess, it can produce reductive sulfur compounds (struck match, smoke to rotten egg, cabbage).
Lees also provide nutrients for microbes such as lactic acid bacteria or Brettanomyces.
Lees ageing increase the time and storage needed. Increase monitoring and labour cost (especially for barriques).
Blending
Blending impact style, quality and price.
It may be done at any time.
Often carried before stabilisation, finishing and packaging.
May blend different grapes, locations, growers, vintages.
What cannot be blended depends on local legislation.
Key reasons for blending are:
- balance. increase or moderate characteristics.
- consistency. is expected by the consumer.
- style. ex rose
- complexity. for greater range of flavours.
- minimising faults. ex. volatile acidity, smoke taint)
- volume
- price. improving the wine can help reach or keep the price point of the wine.
