COMPOSITION OF WINE WEEK 2 Sensory Evaluation 1 use for quiz #1
Dec 30, 2015
COMPOSITION OF WINEWEEK 2
Sensory Evaluation
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Components of Wine
Water: 80 to 95%AlcoholAcidsPolyphenolsSugarsCarbon Dioxide/CO2
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Components of Wine: Acids
Tartaric Acid: -the strongest acid
-Specific to grapes, rarely found in nature
Malic Acid: most prevalent in unripe grapes
Degrades as the grape ripens Can be degraded by lactic bacteria and turned
to lactic acid through malo-lactic fermentation
Together account for 90% of grapes acidity
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Components of Wine: Acids
Help in stabilizing colorReact with alcohol to form esters (aromas)Uplift aromas and flavorsEnhance wine’s ageing potential Help to prevent microbial spoilage Balances residual sugar
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Measuring acid through pH
Strength of acid is measured in pH units in grapes p – power H – Hydrogen ion concentration The property that gives a solution it’s acidity
• The lower the pH the stronger the acid• pH usually ranges between 2.5 and 4. in wine• For every decrease of 1 unit in the pH scale –
strength of acidity increases 10 times• Potassium ions replace Hydrogen ions as the berry
ripens and acids decrease• Values of 3.5 or less are preferable in finished wine
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pH
pH measures the quantity of acids present, and the strength of the acids
Wine pH depends on three main factors: the total amount of acid present, the ratio of malic acid to tartaric acid and the amount of potassium present
Wines that contain little acid and excess potassium show high pH values.
Wine with more tartaric acid, less malic acid, less potassium and more titratable acid has lower pH values.
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Important effects of low pH in wine
Low pH has many important effects: Making sulphur dioxide more effective as an
antimicrobial agent Inhibiting bacterial growth Improving the taste of the finished wine Increases the acid – balancing the wine
pH of approximately 3.4 - 3.5 usually provides the most balanced flavor for red wines
pH for white wines is effective when it is slightly lower (3.0-3.3)
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Organoleptic Characteristics of Acids
Visual: Gives brilliance, reflective quality
Olfactif:Usually not perceivable but malic acid reminds of green apple, and can show up as “minerality” Taste: Has acidic flavor, tart and mouth drying leading to
salivationTactile sensation:
Felt on side of the tongue, plus salivation, mouth watering sensationMalolactic fermentation:
Adds creamy, buttery notes, plus added body/texture
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Recommended Acidity
Dry White Wine - 0.65 % - 0.75 %Sweet White Wine - 0.70 % - 1.0%Dry Red Wine - 0.60 % - 0.70 %Sweet Red Wine - 0.65 % - 0.90 %Fortified Wines - 0.50 % - 0.60 %
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Components of Wine: Polyphenols/Phenolic
Compounds Extracted mainly from grape skins and stems Group of chemical compounds that affect wines color,
texture, astringency and bitterness
Phenolic compounds responsible for red wine color areAnthocyanins – found in pulp cells under the skins of black
grapesIn red wine (200 to 500 mg/l)
Tannins: Large Phenolic compounds determine body and astringency – act as antioxidants and preservatives – precursors to aromatic compounds when wines are aged1 to 3g/l in reds Can also be found in very small quantity in whites(20-30mg/l) if matured in oak barrels due to wood tannins
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Organoleptic Characteristics of Polyphenols
Visual: responsible for the color of red and white wine
Varying levels and specific to each varietalAs wine ages, tannins polymerize and form
sediments for red wines resulting in a lighter color
Color will deepen for whites due to oxidation
Taste: responsible for the astringency of wine
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Astringency vs. Bitterness
Tannins brings astringency and structure Characterized by three sensations:
Constriction of sides of cheeks and gumsDusty, roughing sensation on teeth and gumsDrying sensationCan taste bitter
Bitterness is a flavor – not a feeling like Astringency
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Components of Wine: Alcohol
Mostly ethanol, some methyl alcohol in small quantity
7 to 15% by volume (fortified up to 20%)Issued from fermentationIn most cases will be lower if residual sugar
is present but may still be very high if issued from hot climate
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Organoleptic Characteristics of Alcohol
Visual: contributes to tears andviscosity when combinedwith glycerolTaste: In high quantity,
contributesto sweetness Contributes to mouthfeel
andviscosity and “heat” when
inexcess
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Components of Wine: Sugar
Mostly glucose and fructoseFound in varying degrees in finished wine
(Brix x 0.57 = potential alcohol)Converted to alcohol by fermentationIf detectable, characterized as
Residual Sugar listed as grams per liter (g/l)
Specific to wine type:Dry wine: less than 4 g/l (EU standards)
Sweet wine: can be up to and beyond 50 g/l
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BRIX
Degrees Brix (symbol °Bx) Brix – measurement of sugar in the grape Formula for potential alcohol
Brix x .57 = potential alcohol
Measurement of sugar in the grape will determine how much alcohol that wine will potentially make
It’s the winemaking decision about converting all of the sugar into alcohol.
Some wine with residual sugar remaining will have lower alcohol in them as a result of stopped fermentation
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Organoleptic Characteristics of Sugar
Visual: increased viscosity, increased potential alcohol in finished wine (tears)
Olfactif: Contributes to “ripe or honeyed” aromas but not necessarily detectable
Taste: Has a sweet flavor, rich mouthfeel andincreased palate weight
Increased heaviness/fatness if unbalanced
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Components of Wine: Carbon Dioxide
Two forms:Dissolved (carbonic acids), detectable at
600mg/lFree: slight fizz to large bubbles, over
1000mg/l
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Organoleptic Characteristics of CO2
Visual: bubbles
Olfactif: enhances and uplifts the aromas
Taste: has an acidic/tart flavor
Tactile Sensation: prickle on the tongue and a roughing of the mucus membrane
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Balance-alliance of flavors
Sugar diminishes acid perceptionBitter (from tannin) will reinforce acid
tasteHigh acidity tones-down high alcoholHigh tannins must be balanced by
moderate acidityHigh alcohol volatizes esters and can
distort structure Low alcohol (RS) needs fresh acidity
and/or bright tannins
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Balance of wine
In addition to fruit components, wine balance relies on:
Dry white: 2 structural elements: acidity and alcohol
Sweet white: 3 elements: residual sugar, acidity, alcohol
Red wine:Acidity, Alcohol (sweetness), Tannin
All elements must compliment each other and frame the fruit aromas and flavors
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