Ch 11 Wine Components Flashcards
Wine Components
What are the 8 main components of wine?
- Water
- Acid - tartaric, malic, lactic
- Alcohol (Ethanol)
- Aroma compounds/pre-cursors - from grape, from precursors during ferm, from ferm and by-products, from
other sources - Glycerol
- Residual sugar
- Phenolics
Wine Components
What is main component of wine?
Water = 85% depending on abv, RS and other factors
Wine Components
What is the main alc in wine?
How is it created and what are its characteristics?
What does it contribute to wine?
○ Ethanol - from fermentation
○ Slightly sweet smell
○ Adds fullness to body/mouthfeel
○ Above 14.5%abv -> reduces volatility of wine aromas and adds bitterness; needs fruit concentration to be in
balance
Wine Components
What are the primary acids, where do they come from and what % of acid do they make up?
What are the other non-primary acids and where do they come from?
Primary
* * Tartaric and malic -> come from grape itself
* Make up ~2/3 of acid in warmer climates
Other
* Lactic and acetic -> come from fermentation and MLC
Wine Components
What is volatile acidity and what reaction does it have with other components?
Acetic acid is present at low levels in all wines -> fault when too high
VA comes from acetic acid reacting w/ alcohol -> becomes ethyl acetate
- smells like nail polish remover
Wine Components
What is ethyl acetate?
Reaction of acetic acid w/ alc = VA
Nail polish remover aroma
fault at high levels
Wine Components
What role does acid play in wine?
What happens if too much/too little?
Adds to structure - brings freshness and vibrancy; balances fruit concentration and RS (if any) -> makes wine feel leaner on palate
Too much - too tart
Too little - wine is flabby
Wine Components
What is relationship bet perception of acid and dryness with other components?
Example?
Acid/dryness related to balance of acidity w/other components and to any RS
More acid - tastes drier
Ex - Riesling - tastes dry despite having signif RS (up to 9mg/L) because of high acid
Wine Components
How do levels of individual acids affect tast of wine?
Example?
Tartaric and malic acid most tart, lactic acid softer
Cool climate - more malic = firm acidity which infl its style
E.g., Chard where MLC is blocked
Wine Components
What is relationship between total acidity and pH?
Relationship linked, but not fully correlated
Normally wine w/ higher acidity have lower pH
- other molecules have buffering effect -> potassium
Wine Components
What are 2 main ways of expressing acidity measurement?
- TA in g/L of tartaric acid
- pH level
Wine Components
How is total acidity level measured and expressed - most common and what is normal level?
What is alt measurement?
Most common - TA = sum of all acids -> g/L tartaric
- normal = 5.5 - 8.5 g/L
Alt measure (France) - TA = sulfuric acid -> ratio between sulfuric and tartaric is 1:1.5
Wine Components
What does pH measure, what is its scale, how is it expressed and what is the normal level in wine?
○ pH measures concentration of effective acidity in a solution
○ Normal range for wine - pH of 3-4
○ Inverse scale -> lower means more acid, higher means more alkaline;
○ Logarithmic scale -> pH of 3 is 10x more acidic than pH of 4
Wine Components
What does a lower pH affect in winemaking?
- Promotes microbiological stability
- Increases effectiveness of SO2
- Reds have brighter color
- Enhances age-ability of wines
Wine Components
What are 4 categories of wine aromatic compound types?
- Aromas created from compounds found in grapes
- Aromas created by fermentation due to APCs in grape must
- Aromas from fermentation itself and its by-production
- Aromas from other sources
Wine Components
What are examples of aromas created from compounds found in grapes themselves?
Methoxypyrazines - grassy, green pepper - Sauv Blanc
Rotundone - pepper - Syrah and Gruner
Wine Components
What are aroma pre-cursors?
Examples?
APCs are compounds not inherently aromatic found in grapes - building blocks that become aromatic via fermentation
Examples - many compounds are in grapes bound with sugar as aromaless APCs - become aromatic w/ ferm:
- Thiols - ex 4MMP - boxwood, gooseberry in SB
- Terpenes - fruity and floral aromas - ex linalool and geraniol = grapey aromas/flavors in Muscat
Wine Components
What are main compounds that do not come from grapes but are created by ferm and its by-products?
- Esters - formed by interaction of certain acids and alc
- Acetaldehyde - occurs due to oxidation of ethanol
- Diacetyl - from ferm and especially MLC
- Reductive sulfur compounds - can come from yeast and lees aging
Wine Components
What are esters, how do they form?
What do they add to wine and what wines are they important for?
Example?
Esters are compounds that form by action of yeast in ferm process or from reaction of certain acids w/ alcohol
○ Most are unstable and breakdown a few months after ferm
- Esters create many fresh and fruity aromas -> crucial for aromas of young white wines
- Most common ester = isoamyl acetate = banana aroma if high concentration (Beaj Nouv); also apple, pineapple
- Another common - ethyl acetate - nail polish remover aroma - fault at high levels
Wine Components
What is acetaldehyde and what is another name for it?
Where does it come from?
What does it do in wine?
What type of wine is it key for?
○ Occurs with oxidation of ethanol
○ Aka, ethanal
○ Masks fruity aromas and has stale smell -> usually considered a fault
○ Key positive for fino sherry
Wine Components
What is diacetyl, how is it created and what does it add to wine?
Diacetyl is created by ferm, especially MLC
Adds buttery aromas
Wine Components
What are reductive sulfur compounds, how are they formed and what impact on wine?
○ Yeasts can create these compounds during ferm and/or lees aging
○ Depending on types and levels -> aromas range from struck match (can be positive) to rotten egg (usually a
fault)
Wine Components
What are examples of aroma compounds from “other sources?”
Vanillin - comes from oak, adds vanilla aromas
Eucalyptol - can be volatized from eucalyptus trees by heat and absorbed via grape skin bloom
Wine Components
What does residual sugar add to wine?
Sweetness
Body
Wine Components
What is the EU classification of sweetness levels?
What factors are part of it?
What are labeling requirements?
○ 2 classifications - one for sparkling and one for still wines
○ Terms do not have to appear on labels; some regions encouraging use for consumer clarity
○ 2 key factors ->
- levels of RS
- optionally, higher levels of RS for wine with higher total acidity (expressed in g/L of tartaric acid)
Wine Components
What are EU categories for RS levels, terms and thresholds?
see one note ch 11 or book p 115
Wine Components
What is glycerol?
How big of a wine component is it?
When does is occur and what does it add to wine?
○ Third most abundant component after water and alc
○ Derived from sugar in grapes
○ Occurs in higher levels in bot affected grapes and carbonic wines (less than bot)
○ Adds smoothness to texture and fullness to body, slightly sweet taste
Wine Components
What are phenolics?
○ Come from grape skins, stems and seeds
○ Include anthocyanins (red and sometimes blue color pigments) and tannins
Wine Components
How do tannins work to create dry sensation?
How is then perception of tannin influenced by other wine components?
Tannins bind with saliva to create dry/astringent feel -> very complex not well understood
wine components infl on tannins:
○ a little RS -> can make tannins seem softer
○ Acid-> can make tannin more astringent
○ Tannins also interact with compounds in wm and mat, changing their composition and how they are perceived
○ Unripe tannins - bitter and never desirable
○ Level and nature of tannins key part of quality in red wines
