Ch. 11: Wine Components Flashcards
Ethanol
The predominant alcohol in wine. It contributes a sense of sweetness and bitterness in wine, as well as warmth in the mouth and throat. High alcohol levels (14.5 and above) reduce the volatility of wine aromas and increase the sense of bitterness. High alcohol wines need to be balanced by concentrated fruit.
Volatile acidity
Mainly refers to acetic acid, which has a vinegar smell. Acetic acid also combines with alcohol and form ethyl acetate, which gives off a ‘nail polish’ aroma. It is present in all wines and is only considered a fault in excess, where it gives off a pungent smell of nail polish and/or vinegar.
It is caused by bacteria, exposure to oxygen, and inadequate levels of SO2. It can be managed by keeping the winery very clean, keeping vessels topped up to minimize oxygen exposure, maintaining adequate levels of SO2, and excluding damaged grapes.
Total acidity
The sum of all acids in the wine (tartaric, malic, acetic, lactic, etc.), Most dry wines have between 5.5 - 8.5 g/L of acid.
Note: pH levels are inversely correlated concentrations of acidity, with low pH indicating concentrated acidity.
Wines with low pH increase the microbiological stability, increase SO2 effectiveness, give red wines a bright red color, and enhance the wine’s ability to age well.
Methoxypyrazines
A wine aromatic created by grapes, it gives an grassy, green pepper aromas, as in Sauv Blanc.
Rotundone
A wine aromatic created by grapes which gives wine a peppery aroma, as in Syrah.
Aroma precursors
Aroma compounds found in the grape must that become aromatic during fermentation.
Thiols
A compound found in grape must that is an aromatic precursor, which becomes aromatic during fermentation. Thiols (4MMP) give a ‘box tree’ aroma to Sauv Blanc.
Terpenes
A compound found in grape must that is an aromatic precursor, which becomes aromatic during fermentation. Terpenes give floral, fruity aromas to wine. Grapey aromas in Muscat are the result of terpenes.
Esters
An aroma created by the fermentation process, it imparts fresh, fruity aromas to wine, and is therefore an essential component in young wine. A classic example is the banana smell in Beaujolais Nouveau, but esters also produce many other aromas, such as apple, and pineapple.
The majority are created through the action of yeasts in the fermentation process, and are formed by the reaction of certain acids and alcohols.
Acetaldehyde
An aroma created by the oxidation of ethanol. It masks fruity aromas and has a stale smell that is regarded as a fault in most wine. However, it is a desirable and distinctive aroma in fino Sherry.
Diacetyl
Contributes a buttery aroma to wine, and is formed during the fermentation process, especially malolactic conversion.
Vanillin
One of the aroma compounds that can be derived from oak aging, it gives off vanilla aromas to the wine.
Eucalyptol
An aroma that is passed off in vapor from Eucalyptus trees by heat and absorbed into grape skins of grapes in nearby vineyards .
Residual sugar
The amount of sugar left over in the wine after fermentation. Dry wines will often have a small amount of residual sugar (2-3 g/L), while off-dry to sweet wines will have a lot more (Sauternes can have 150 g/L, PX 400).
RS contributes to the level of sweetness in a wine, and also gives it more body.
Dry/sec/trocken
Up to 4g/L RS, OR
Not exceeding 9g/L if total acidity is within 2g below RS content.
For example, a wine can be labeled ‘Sec’ if it has 9g/L of sugar, and 7g/L of total acidity.
