Maturation Flashcards
Oxygen in maturation
Generally oxidation leads to a gradual reduction in primary aromas and development of tertiary (dried fruits, nuts). This can be good (if wine has aging potential) or negative (if they are not pleasant).
Can influence color of wine; whites become darker moving from gold to brown. Exposing young red wines to oxygen can result in color stability and intensity. Anthocyanins bind with tannins which protects them from being bleached by SO2 or adsorbed by yeast lees. After much exposure reds become paler and browner.
Can soften tannins for red wines.
Speed of oxidation influenced by amount of exposure, compounds in the wine, temperature. Full exposure (open tank) will oxidize quicker than closed barrel. Reds can withstand a higher level of oxygen than whites before showing signs of oxidation due to higher content of anti-oxidative compounds like tannins. Hence reds are matured longer (12 - 24 mo) than whites (6 - 12).
Oxidation is a key component of some wine styles like oloroso sherry
Wooden Vessels and Oxygen
Small wooden vessels are the traditional and most common method to have a slow gradual exposure to oxygen.
Some oxygen is released from the pores of the vessel in the first month. Then a very small amount continues to pass through the gaps b/n staves and bung hole. Most exposure though happens through transfers; racking, lees stirring, topping up.
Some wine is lost when maturing in wood as water and alcohol seep into the wood and then evaporate leading to a gradual concentration of other elements.
Small barrels have a large surface area to volume ratio increasing rate at which wine is lost and so need frequent topping up. This frequent topping up leads to more exposure (vs larger vessels).
Micro-Oxygenation
Can be a cheaper alternative to the oxidation of barrel aging.
Involves bubbling oxygen through wine in doses of mg/L per month. Generally done in stainless over a number of months post alcoholic fermentation.
Used to be just for inexpensive but now being used more.
Increases color stability and intensity, soften tannins, improve texture, and reduce unripe herbaceous flavors. Provides oxidative impact of barrels in less time and with less money. and can be controlled better. If used with oak alternatives (chips) they may be integrated better.
However any increase in oxygen can create a growing environment for spoilage bacteria like acetic acid bacteria and Brettanomyces.
Relatively new technique
Role of Wood In Maturation
Newly made wood vessels have extractable compounds like tannins and aroma compounds. The levels depend on:
Age of the Vessel: New wood contains extractable compounds. Each time a barrel is used the level of extractables decreases. Usually loses 50% after first year. By the 4th year will have very little left. Some winemakers don’t use any new oak at all to avoid conflicts b/n the flavors. Where is it used it is typically a proportion of the blend.
Size of Vessel: small ones like barriques (225L) hold a small vol of liquid compared to surface area. extraction from wood and exposure to oxygen are greater in small vs large.
Type of wood: Oak most common (easy to shape, nice flavor, water tight). Most European (French, Hungarian, Russian, Slavonian) or American. Both have sig vanillin. American has more lactones, for coconut and in general higher intensity of aromas. Euro is subtler but more tannin.
Length of time: longer time more extraction and oxygen exposure.
Cost: Expensive; don’t hold much so need a lot, monitoring, lees stirring, racking, spoilage org’s love wood, slow (1-2 yrs)
Oak Stuff
European production is more expensive. American 300Euro - 600; French 600 - 1200. Euro must be split to make staves; American sawn so more can be made from same amount. American grows quicker
Slower growing have tighter grains. Continental climates (Russia, Hungary) are slowest and tightest grains. This slows down the extraction of compounds and tannin.
First wood is seasoned (outside 2 - 3 years). Lowers humidity, reduces bitterness, increases some flavor compounds (cloves). Staves are heated so they can be bent. This transforms tannins and aroma compounds. Temperature and length is toasting (light, med, heavy). Notes of spice, caramel, roasted nuts, char, smoke. Pronounced in heavy toasting. Many cooperages have a house style and wineries may use lots to create complexity.
Oak Alternatives
Oak chips - placed in a permeable sack left to soak.
Oak staves - attached to sides of tanks or float
Diff species, seasoning, toasting.
Much cheaper and less labor intensive, large surface area for quick impact.
Some use micro-ox along with oak alternatives for better integration
Role of Lees
Sediment at bottom of wine vessel, including dead yeast, dying yeast, bacteria, grape fragments, precipitated tannins, nutrients.
Gross lees form in first 24h (larger heavier stuff); smaller settle more slowly and known as fine lees.
Keeping wine in contact with: after fermentation yeast cells break down slowly (autolysis) releasing compounds contributing flavor, body, texture. Some bind with phenolics reducing color and softening tannin. Also can bind with wood tannins and flavors and can reduce astringency and modify wood flavors.
In white wines more sig; yogurt, dough, bread, biscuit. Helps stabilize against unstable proteins that can cause haze. Protect against oxygen to maintain a slow controlled oxidation during maturation and lowering need for SO2. But too thick (gross lees) can produce sulfurous compounds. Can be pleasant at low concentration (struck match), but unpleasant at high (rotten eggs) called reduction.
Provide nutrients for microbes and can help lactic acid grow or brett.
Need to be monitored (maybe stirred) for labor.
Blending
Mixing two or more batches of wine; often just prior to finishing and packaging.
Grape varieties, locations, owners, vintages, diff treatments, diff vessels same treatment.
Balance: increase or moderate characteristics (i.e. acid)
Consistency: assure a certain volume of consistent product or across years (champers)
Style: house style, quality levels
Complexity
Minimize faults
Volume
Price: i.e. adding trebbiano to Chard to keep price points low
Usually starts with trials in beakers, requires skill and experience as blending young wines which will change with age
Best before stabilization as instabilities might arise from blending. i.e. pH could change which impacts tartrate stability
