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Sensory Evaluation

Sensory Evaluation

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Sensory Evaluation

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  1. Sensory Evaluation Composition of Wine Week 2 use for quiz #1

  2. Components of Wine • Water: 80 to 95% • Alcohol • Acids • Polyphenols • Sugars • Carbon Dioxide/CO2 use for quiz #1

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  4. 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 use for quiz #1

  5. Components of Wine: Acids • Help in stabilizing color • React with alcohol to form esters (aromas) • Uplift aromas and flavors • Enhance wine’s ageing potential • Help to prevent microbial spoilage • Balances residual sugar use for quiz #1

  6. 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 use for quiz #1

  7. 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. use for quiz #1

  8. 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) use for quiz #1

  9. 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 salivation Tactile sensation: Felt on side of the tongue, plus salivation, mouth watering sensation Malolactic fermentation: Adds creamy, buttery notes, plus added body/texture use for quiz #1

  10. 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 % use for quiz #1

  11. 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 are Anthocyanins – found in pulp cells under the skins of black grapes In 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 aged 1 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

  12. Organoleptic Characteristics of Polyphenols Visual: responsible for the color of red and white wine • Varying levels and specific to each varietal • As 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 use for quiz #1

  13. Astringency vs. Bitterness Tannins brings astringency and structure Characterized by three sensations: • Constriction of sides of cheeks and gums • Dusty, roughing sensation on teeth and gums • Drying sensation • Can taste bitter Bitterness is a flavor – not a feeling like Astringency use for quiz #1

  14. Components of Wine: Alcohol • Mostly ethanol, some methyl alcohol in small quantity • 7 to 15% by volume (fortified up to 20%) • Issued from fermentation • In most cases will be lower if residual sugar is present but may still be very high if issued from hot climate use for quiz #1

  15. Organoleptic Characteristics of Alcohol Visual: contributes to tears and viscosity when combined with glycerol Taste: In high quantity, contributes to sweetness Contributes to mouthfeel and viscosity and “heat” when in excess use for quiz #1

  16. Components of Wine: Sugar • Mostly glucose and fructose • Found in varying degrees in finished wine (Brix x 0.57 = potential alcohol) • Converted to alcohol by fermentation • If detectable, characterized as Residual Sugarlisted 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 use for quiz #1

  17. 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 use for quiz #1

  18. 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 and increased palate weight Increased heaviness/fatness if unbalanced use for quiz #1

  19. Components of Wine: Carbon Dioxide Two forms: • Dissolved (carbonic acids), detectable at 600mg/l • Free: slight fizz to large bubbles, over 1000mg/l use for quiz #1

  20. 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 use for quiz #1

  21. Balance-alliance of flavors • Sugar diminishes acid perception • Bitter (from tannin) will reinforce acid taste • High acidity tones-down high alcohol • High tannins must be balanced by moderate acidity • High alcohol volatizes esters and can distort structure • Low alcohol (RS) needs fresh acidity and/or bright tannins use for quiz #1

  22. 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 use for quiz #1