Ch. 14 Maturation

Question 1

What are the key factors that influence wine during maturation?

Answer 1

• oxygen
• new wood
• yeast lees
• blending

Question 2

What is the role of oxidation in maturation?

Answer 2

• reduction of primary aromas, development of tertiary aromas (can impact quality)
• color - white wines become darker, red wines become lighter - exposing young red wine to O2 can result in greater color stability (imp for PN for ex)
• softening of tannins (for reds)

Question 3

What factors influence the speed of oxidation?

Answer 3

• amount of oxygen exposure - fully exposed vs gradual exposure
• compounds in the wine - phenolics
• temperature - warm temps increase speed of oxidation

Question 4

Why are red wines usually matured for longer than white wines?

What is common pre-bottling maturation for reds and whites?

Answer 4

Tannins. They protect wines against oxidation, so can withstand more oxidation than whites before any effects are apparent.

Reds- 12-24 months pre botting maturation
Whites - 6-12 moths pre botltling

Question 5

How do wooden vessels contribute to oxidation?

Answer 5

Small wooden vessels allow a slow, gradual exposure to oxygen. This is because:

1. small amount of oxygen release from pores of vessel within first month of use
2. Oxygen passes through bung hole and/or staves, wood itself
3. Transfer of wine - racking, lees stirring, topping up - GREATEST EXPOSURE
4. Some water and alcohol evaporate within staves of wood, concentrating other components of wine - smaller vessels lose wine at higher rate, increases frequency of topping up

Question 6

What is microoxygenation?

Answer 6

A cheaper alternative to maturing wine in barrels that involves bubbling oxygen through wine. Generally carried out in stainless steel tanks.

Question 7

What are benefits and drawbacks of microxygenation?

Answer 7

\+
increase color stability and intensity 
soften tannins
improve texture
reduce presence of any unripe/herbaceous flavors
quicker and cheaper than using barrels
more control than when using barrels
can help integrate influence of oak if used with oak alternatives

-
increasing O2 levels can encourage spoilage organisms like acetic acid bacteria and Brett
New technique, more research required

Question 8

Storage temps for red and white wine

Answer 8

White: 8-12C (46-54 F)
Red: 12-16C (54-61F)

Question 9

What is effect of temperature and humidity on wine oxidation?

Answer 9

Stable, cool temps slow down the rate of oxidation and threat from spoilage organisms.

Low humidity and warm temps increase the rate of wine loss –> undesirable bc it reduces volume of wine and barrels need topping up more often (labor cost), risk of oxidation is higher

Low humidity - water inside barrel will want to move outside where there is lower humidity so it will evaporate - higher concentration of alcohol

Wines usually matured in cool cellars of constant temp and humidity.

Question 10

What factors influence the level and type of compounds extracted from wood

Answer 10

• Age of vessel - new wood contains more (often too many depending on wine style) extractable compounds than used wood; max usage is typically 4,
• Size of vessel - proportion of liquid to surface area of vessel; greater ratio/effect in 225 l barriques than large foudres so extraction and exposure to O2 is greater
• type of wood- American vs French oak
• American: more lactones (aromas of coconut), more intense aromas/flavors, cheaper
• European: more tannins, more expensive than American wood
• tightness of grain - tighter grain slows down extraction of compounds
• production of vessel - level of toasting (temp + length of heat exposure) contributes notes of spice, caramel, char, smoke, cooperages have house style

Question 11

How does length of time in wood affect level and type of compounds extracted?

Answer 11

• Longer the wine is aged in a wooden vessel, the greater the extraction of compounds and exposure to oxygen
• Extraction varies at different points in ageing process, so longer time spent in wood increases diversity of compounds

Question 12

What factors contribute to cost of maturation in wood?

Answer 12

• expensive, typically used to mid priced, premium or super premium wines

1. barrels are expensive to buy
2. labor intensive to monitor wines in separate barrels, perform operations like lees stirring, racking etc; cleaning also imp
3. ROI slow - barrel maturation is slow process

Question 13

Different oak alternatives and benefits

Answer 13

Oak chips - placed in permeable sack to soak in wine
Oak staves - attached inside SS or concrete vessel to float

+
diversity in species of wood, seasoning, toasting level
cheaper
can be added to large tank of wine, less labor required
quick to have effect
effective esp when used with micro-oxygenation

Question 14

What are lees?

Answer 14

The sediment that settles at the bottom of a wine vessel.

Made up of dead yeast, dying yeast and bacteria, grape fragments, precipitated tannins, nutrients and other insoluble compounds.

Question 15

What is difference between gross lees and fine lees?

Answer 15

Gross lees- sediment that forms quickly within 24h of end of fermentation, made up of larger, heavier particles and generally removed during first racking

Fine lees - smaller particles that settle more slowly, managed by periodic rackings

Question 16

What are the effect of lees on still wine during maturation?

Answer 16

1. When they break down during autolysis, they release compounds that contribute flavors, body and texture to the wine - aromas like dough, biscuit, toasted bread
2. Reduce colors, soften tannins (bind w phenolic compounds)
3. Reduce astringency and modify flavors from wood (bind w extractable compounds)
4. Increase microbiological stability of white wines against proteins that cause hazes
5. Protect wine from oxygen - maintain controlled oxidation during maturation, lowering need for SO2

Question 17

What are hazards/drawbacks/considerations for lees maturation?

Answer 17

1. If lees layer is too thick, it can produce volatile, reductive sulfur compounds which may contribute unpleasant aromas like rotten eggs (reduction)
2. Nutrients for microbes - can encourage organisms like Brett
3. Increase time stored at winery, final cost of wine
4. Require regular monitoring, stirring – labor

Question 18

Describe the process of racking

Answer 18

The process of transferring wine from one vessel to another with the aim of removing sediment from the wine (gross lees, fine lees, grape skin, tartrate crystals)

Wine is removed from original vessel by a valve at the bottom (above top of sediment) and pumped into new vessel.

Can be oxidative process - some red winemakers will splash wine 
Protect wines (aromatic/fruity wines) - using inert gas to push wine out rhough hose - Albarino/Lagar da Condesa

Can be carried out once or several times

Question 19

What does blending refer to? What are different types of wine that can be blended?

Answer 19

Blending - mixing together of two or more batches of wine; most often carried out prior to finishing and packaging

Blending involves combining wines:

• from diff grape varieties
• from diff locations
• from diff grape growers/cooperatives
• diff vintages - blending in young wine
• treated diff in winery (press fractions, matured in oak vs ss, etc)

Depends on local legislation

Question 20

What are the key reasons for blending wines?

Answer 20

• Balance - Merlot + CS
• Consistency - ensure certain volume of consistent product
• Style - “house style”
• Complexity - two or more parcels
• Minimise faults - showing VA, sterilize then blend w another
• Volume- poor vintages, need viable volumes
• Price - create certain style/quality within expected profit