The Role of Oxygen in Maturation Flashcards
Why are wines like Sauv Blanc or Pinot Grigio stored in SS tanks?
To protect them from oxygen.
During maturation, what effect does oxygen play on the different types of aromas?
Primary aromas reduce.
Tertiary aromas increase.
What influence can oxygen have on the color of red wine?
Exposing a young red wine to oxygen can help fix the color and protect against SO2 bleaching.
Over time, exposure to oxygen will make the color fade and turn brown.
What influence does exposure to oxygen have on the color of white wine?
White wines become darker, from gold to brown.
What effect does oxygen have on tannins in red wine during maturation?
Oxygen results in the softening of tannins over time. This may be linked to anthocyanin and tannin bonding.
What affects the speed of oxidation of a wine?
- amount of oxygen exposure
- compounds in the wine
- temperature
- many other factors
Why do red wines oxidize more slowly than white wines?
Higher levels of antioxidative compounds tannins, than white wines.
How is oxidation apparent in deliberately oxidized wines?
- brown color
- lack of fresh fruit aromas and flavors
- flavors of nuts and dried fruits
How does oxygen enter the wine during maturation in oak vessels?
- some oxygen is released from the pores of the wood during the initial month after filling
- a small amount of oxygen passes through the bung hole
- during transfer or racking of the wine
Why do barrels often need topping up?
Water and alcohol impregnate the wood, and then evaporate. Topping up is required to avoid excess ullage and excessive oxidation.
However, introduction of wine into the barrel results in small amounts of oxygen entering the wine.
Why is oxygen exposure greater in small barrels?
Smaller barrels have greater wood to wine ratio.
Wine evaporates more quickly.
Small barrels require more frequent topping up. Quantity of oxygen added with the top up is relatively larger per volume of wine in a smaller barrel than a large one.
What is a cheaper option than barrels, for introducing oxygen to a wine during maturation?
Micro-oxygenation
Define micro-oxygenation.
The bubbling of oxygen through wine.
How is micro-oxygenation performed?
Carried out in SS tanks for a number of months post-fermentation.
Styles of wine using micro-oxygenation?
Generally used on inexpensive to mid-priced wines.
Growing number of premium and super-premium wines using this technique.
What positive effects is micro-oxygenation thought to have on red wines?
- stabilizes color
- softens tannins
- improves texture
- reduces presence of unripe flavors
Why must care be taken with micro-oxygenation techniques?
Increased oxygen in the wine may encourage spoilage organisms.
Relatively new technique, and so it is yet to be seen how it affects wine during long term aging.
Why are temperature and humidity important in the storage facilities of maturing wines?
Cool temps slow the rate of oxidation and evaporation.
Humidity is controlled to slow evaporation to reduce volume losses and alcohol rises (as water evaporates more quickly in low humidity)/
