WINE AGEING Flashcards
Why would you age wine? (3)
To soften wine structure
To get maturation flavours
To get stability (color, tartric precipitation, proteins etc)
When does aging begin?
At the moment alcoholic fermentation is stopped
What is another way to describe the process of ‘wine ageing’?
Controlled oxidation process
What are the 3 different types of oxidation?
Chemical
Enzymatic
Microbial
Define chemical oxidation
reaction of polyphenols with oxygen. Converted into quinones and Hydrogen peroxide (H2O2). This oxygen containing compound is a strong oxidising agent which converts ethanol into acetaldehyde
Define enzymatic oxidation
Juice and must is oxidised by an enzyme that is called polyphenol oxidase (PPO) and Laccase in case of botrytis. Phenols are turned into quinones. Easily inhibited by SO2
Define microbial oxidation
Spoilage by Acetic Acid Bacteria (AAB), film yeasts (Candida) and Brettanomyces (Brett). Depending on oxygen.
What is the optimal balance between anthocyanin and tannin?
1/3 or 1/4
The higher the poly phenolic concentration the..
The higher the resistance against oxidation
The higher the polymerisation level, the…
The slower the oxygen consumption
The higher the pH, the..
The faster the oxidation
Which factors are affecting oxygen dissolution in wine? (3)
Temperature
Dissolved CO2
Lees and turbidity
How does temperature influence the amount of dissolved oxygen in wine?
The lower the temp, the higher amount of dissolved O2. Any manipulation or transfer below 10C should be avoided.
What is the ideal temperature for wine manipulation?
Between 15-20C
What dissolves easier in wine, O2 or CO2?
CO2 (around x 100)
How do lees and turbidity protect the wine from oxygen?
Fresh lees have a high reductive potential. The high turbidity will cause a higher O2 consumption
What is the effect of higher turbidity on SO2?
It binds SO2 and so reduces the free SO2
Describe reductive ageing
Protective winemaking approach focused on minimal oxygen in the environment.
Which factors/winemaking methods influence oxygen management during ageing? (6)
SO2
Temperature
Wine inserting gas
Rackings (air contact management)
Choice of vessel
Duration of ageing
Which wine will react quicker with oxygen, white or red? Why?
Red. The polyphenols react with oxygen. It consumes the dissolved oxygen so it cannot oxidise. The sooner the O2 is dissolved the less risk of oxidation. White will consume oxygen in 50 days, red will do it in 10 days.
Can enzymatic oxidation also occur in wine or only in must? Why?
Only in must. Because the enzymes live on the grape skins. The enzyme polyphenol oxidase (PPO) will cause browning of the juice. With the addition of SO2 after pressing those are inhibited.
How does pH relate to the addition of SO2 or your active SO2?
The higher the pH, the lower the acidity, the more (active) SO2 you need.
With microbial spoilage, what do Acetic acid bacteria produce?
Increase of: Ethylacetate (glue/nailpolish) and acetaldehyde (bruised apple/nuts)
Why do red wines have a higher risk of Brett than white wines?
Due to higher pH
What is the only way to prevent Brett?
To have zero fructose or glucose at the end of alcoholic fermentation
At which phase is the wine the most vunerable for Brett yeast spoilage?
When there is no other active yeast anymore. So after AF, during the lag phase.
How do BDX wines being ‘rushed’ ready for en primeur tastings?
Small batches in oak barrels
Inoculated MLF
Polyphenols and mannoproteins with O2 increase the polymerisation and softness of the wine.
What are two common types of ‘film yeast’?
Candida
Picha
What is typical about film yeasts?
They cover the surface from the wine in barrel that is not topped up fully. It produces volatile esters while consuming sugars and ethanol.
