Chapter 11 Wine Components Flashcards
Define Ethanol
The predominant alcohol in wine: one of the main components of wine created during fermentation. It has a sweet smell.
How does ethanol affect the wine?
Contributes:
* Sense of sweetness and bitterness
* Gives oral warmth
* Fullness of the body of the wine
* Mouthfeel
* Reduces volatility of aromas and increases sense of bitterness above 14,5%
Define Volatile acidity
Mainly refers to the presence of acetic acid (vinegar smell) present in wines in low concentration and can be a fault when in excess.
What acids can be present in the wine and where do they come from?
- Tartaric (grape)
- Malic (grape)
- Lactic (malolactic conversion)
- Acetic (fermentation)
Define total acidity
The sum of all acids expressed in grams per liter (g/L) in tartaric acid. Total acidity is around 5.5-8.5 g/L for wines.
What does acetic acid interacts with?
Acetic acid interacts with the alcohol in the wine and becomes ethyl acetate (Hal varnish remover smell). It can be a fault when in excess.
Define pH
pH is a scale of measurement for the concentration of the acidity. Wines have a pH of 3-4.
How does acidity affect the style of the wine?
- It contributes to the structure of the wine.
- Makes the wine refreshing.
- High acid makes a wine feel leaner on the palate.
- Too much acidity and the wine tastes tart.
What does high acidity / low pH do to the wine?
- Increases the microbial stability.
- Increases the effectiveness of SO2.
- Gives red wines a bright red color.
- Enhances a wine’s ability to age well.
Define Methoxypyrazines
One of the aromas that come from grapes. It gives aromas of grass and green pepper. Present in Sauvignon Blanc.
Define Rotundone
One of the aromas that come from grapes. It gives aromas of pepper. Present in Syrah, Gruner Viltliner.
Define Aroma Precursos
Compounds that are not aromatic but will become aromatic during fermentation.
Define Thiols
A category of aromatic compounds that are released during fermentation. e.g. 4MMP that gives box tree aromas in Sauvignon Blanc.
Define Terpenes
A category of aromatic compounds that are released during fermentation giving fruity and floral aromas. e.g. linalool and geraniol contribute to the grapey aromas of Muscat.
Define Esters
An aromatic compound formed by the reaction of certain acids and alcohols. The majority are created through the action of yeast in the fermentation process.
How does Esters affect the wine?
They are responsible for fresh and fruity aromas in wines. Important in white and young wines. Most esters are unstable and will break down a few months after fermentation.
What is the most common type of Esther?
Isoamyl acetate which gives aromas of banana when in high concentration (e.g. Beaujolais nouveau)
Define Acetaldehyde
An aromatic compound that occurs due to oxidation of ethanol (aka ethanal) Important in Fino Sherry but is a fault in most wines: mask fresh fruit aromas and has a stale smell.
Define Diacetyl
An aromatic compound produced during fermentation and especially malolactic conversion. Contributes to a buttery aroma.
Define Vanillin
Aroma compound that gives aromas of vanilla by aging wine in new oak barrels.
Define Eucalyptol
Aroma compound which can be volatized from eucalyptus trees by heat and absorbed in the waxy layer of the skins of grapes. May be a defect in wines.
Define Residual sugar
The amount of sugar in the wine. It contributes to the body as well as sweetness.
* Dry wines have 2-3 g/L
* Sauternes 150 g/L
* Pedro Ximenez 400 g/L
Define Dry/sec/trocken
EU Law - up to 4 g/L RS
Up to 9 g/L if total acidity expresed as grams of tartaric acid per liter is not more than 2 g below RS content.
- < 4 g/L
- < 9g/L if tartaric acid < 7g/L
Define medium dry / Demi-sec / halbtrocken
- 4 < Medium dry < 12 g/L
- < 18 g/L if tartric acid < 8 g/L
