D11: Wine Components Flashcards
Name the components which come directly from grapes, from fermentation or are added in during wine making
Water Alcohol Acids Aromatics Residual Sugar Glycerol Phenolics
What percentage of wine is water?
85%
What does the % of water depend on?
ABV
Level of residual sugar
Other factors
What does alcohol present as in wine?
Ethanol
Facts about Ethanol
- formed during fermentation
- predominant alcohol in wine
- sweet smell
- contributes to aromas of wine
What does Ethanol contribute to wine?
- bitterness
- sweetness
- oral warmth
- fullness of body
What do alcohol levels above 14.5% do?
- reduce volatility of wine aromas
- increase sense of bitterness
- NEED good fruit concentration to balance out high alcohol
What does acidity contribute to in final wine?
- structure of wine
- makes it refreshing
- can make wine seem leaner
- affects taste
What does acidity need to be balanced with?
- good fruit concentration
- if necessary, residual sugar
wine with too much acidity can taste…
tart
wine with not enough acidity can taste…
flabby
Give an example of how acidity levels can affect taste
German Riesling - very high acidity can make wine with residual sugar (9g/L) taste dry
Name three types of acid
Tartartic Acid
Malic Acid
Acetic Acid
Tartaric and Malic Acid
- comes from the grape
- makes up approx 2/3 total acidity in wine
What does volatile acidity mainly refer to?
Acetic acid
What smell does Acetic Acid give?
Nail varnish remover
Is volatile acidity present in all wines?
Yes - in low concentrations
- only becomes a fault when excessive
What is Acetic Acid?
- reacts with alcohol in wines
- becomes Ethyl Acetate
what is the usual pH level of wines with high acidity?
low pH
What is ‘Total Acidity’?
Sum of all acids present in the wine
- usually expressed in g/L
What is the typical level of total acidity?
5.5-5.8 g/L
What is pH?
scale of measurement for concentration of effective acidity of a solution
What is the usual pH range for wine?
3-4
What does a lower pH mean?
lower the number, the more concentrated the acidity so the sharper the wine
What scale is pH on?
LOGARITHMIC SCALE
- pH3 is 10x more acidic than pH4
What does a low pH equal?
- increases microbiological stability of wine
- increases effectiveness of SO2
- gives red wine bright colour
- enhances age-ability
Do wines contain both AROMATIC and NON-AROMATIC compounds?
Yes
Where does aromatic complexity come from?
both aromatic and non-aromatic compounds and how they interact with each other
What are the FOUR sources of aromatics and non-aromatics for wine?
- grapes
- from aroma precursors present during fermentation
- originate in fermentation and its by-products
- other sources (e.g. oak, presence of aromas in vineyards)
What aroma compounds come from grapes?
Methoxypyrazines
Rotundone
What aroma precursors are present during fermentation in the grape must?
Thiols
Terpenes
What aromas compounds originate in fermentation and its by-products?
Esters
Acetaldehyde
Diacetyl
Yeast
What are other sources of aroma compounds?
Vanillin
Eucalyptol
Methoxypyrazines
- from grapes
- Sauvignon Blanc
- grassy, peppery aromas
Rotundone
- from grapes
- Syrah
- Gruner Veltliner
- peppery aromas
Thiols
- from aroma precursors present during fermentation
- released during fermentation
- e.g. 4MMP - gives box tree aromas in Sauv Blanc
Terpenes
- from aroma precursors present during fermentation
- give fruity and floral aromas
- e.g. LINALOOL and GERANIOL which give Muscat grapey aroma/flavour
Name 2 Terpenes
Linalool
Geraniol
give Muscat grapey aroma/flavour
Esters
- formed by reactions of certain acids and alcohols
- created through action of yeasts in fermentation process
- responsible for fresh/fruity aromas
- v imp in young wines
- ISOAMYL ACETATE: gives banana aroma (e.g. in Beaujolais nouveau)
- ETHYL ACETATE
- mostly unstable and breakdown a few months after ferm
Name 2 Esters
Isoamyl Acetate (Beaujolais Nouveau) Ethyl Acetate
Acetaldehyde
- originate in fermentation and its by-products
- occurs due to oxidation of ethanol
- AKA ETHANAL
- masks fresh fruit aromas
- very stale smell: smells like a fault
- very imp in smell in FINO sherry
Diacetyl
- originate in fermentation and its by-products
- produced during ferm (esp during MLC)
- gives buttery aroma
Yeast
- originate in fermentation and its by-products
- in certain conditions, can produce reductive sulfur compounds during ferm and lees ageing
- can smell like struck match or rotten eggs
Vanillin
- comes from another source
- gives vanilla aromas
- comes from ageing wine in new oak barrels
Eucalyptol
- volatized from eucalyptus trees by heat
- absorbed in waxy layers of skins of grapes in vines so can come through into final must
Name the four stages of the Vincente Ferreira Model
Common Compounds in all wines
- aromas produced during fermentation e.g. Ethanol, higher alcohols, some acids
Impact Aromas
- specific aromas that can be recognised e.g. 4MMP and Rotundone
Non-volatile wine matrix
- non-volatile compounds that affect the way the aromatic compounds are sensed
Contributory Aromas
- aroma compounds that are below the normal individual perception threshold but make a contribution when they are with other compounds found in wine e.g. vanillin, acetate, ethyl
What is the usual level of residual sugar for a dry wine?
2-3g/L
What is the usual level of residual sugar for Sauternes?
150g/L
What is the usual level of residual sugar for PX?
400g/L
What are the four levels of EU classification of sweetness?
Dry - Sec - Trocken
Medium dry - demi-sec - halbrocken
medium or medium sweet - moelleux - lieblich
Sweet - doux - suss
Dry
Dry - Sec - Trocken
up to 4g/L RS
Cannot exceed 9g/L provided that total acidity expressed as grams of tartartic acid per litre is not more than 2g below residual sugar content
EXAMPLE: a wine with 9g/L RS can be labelled SEC if it has 7g/L total acidity
What does the EU Sweetness Classification take account of?
1) level of residual sugar
2) higher level of residual sugar for wines with higher total acidity
Medium dry
Medium dry - demi-sec - halbrocken
more than 4g/L and not more than 12g/L
not exceeding 18g/L provided that total acidity expressed as grams of tartaric acid per litre is not more than 10g below RS content
Medium or Medium Sweet
medium or medium sweet - moelleux - lieblich
more than 12g/L
not exceeding 45g/L RS
Sweet
Sweet - doux - suss
- at least 45g/L RS
What is the most abundant part of wine after water and alcohol?
Glycerol
Where is glycerol derived from?
Sugar in grapes
When are glycerol levels higher?
1) botrytis affected grapes
2) wines made through carbonic maceration
what does glycerol contribute to?
1) smoothness to texture of wine
2) perfection of fullness of body
Where are phenolics found?
1) skins
2) seeds
3) stems
What do phenolics include?
Anthocyanins
Tannins
What do tannins do?
1) bind with proteins in mouth which give a drying sensation on the palate
2) react with other compounds in winemaking and maturation, which changes their composition and how they are perceived
What alters the perception of tannins?
other compounds in wine e.g. residual sugar, acidity etc
Unripe tannins are…
Bitter
Undesirable
