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Lecture 6:

Lecture 6:. Overview of Red Wine Processing. Reading Assignment: Chapter 5, pages 221-243. The Basic Steps of Red Wine Production. Crushing, destemming Must to tank Fermentation/Maceration Pressing and Draining Finish of Fermentation. Red Wine Production Types of Fermentation. Grapes.

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Lecture 6:

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  1. Lecture 6: Overview of Red Wine Processing

  2. Reading Assignment: Chapter 5, pages 221-243

  3. The Basic Steps of Red Wine Production • Crushing, destemming • Must to tank • Fermentation/Maceration • Pressing and Draining • Finish of Fermentation

  4. Red Wine ProductionTypes of Fermentation Grapes Juice Must Whole Cluster Blush No Stems + Stems Atmosphere Wine CO2 Juice

  5. Principle Red Wine Varieties in California (% production) • Zinfandel 23% • Cabernet Sauvignon 20% • Merlot 18.3% • Barbera 0.6% • Grenache 0.6% • Rubired 0.5% • Pinot noir 0.5% • Carignane 0.4%

  6. Red Wine: Fermentation on the Skins • To extract pigments and other phenolic compounds in grape skin cells • Use of ethanol of fermentation to increase extraction • Use of cap management strategies to increase extraction

  7. Methods of Cap Management • Rotary tank • Punch down • Pump over

  8. Rotary Tank

  9. Punch Down

  10. Submersion A variation of the punch down technique is total submersion of the cap.

  11. Pumping Over The process of using fermenting juice from the bottom of the tank to bathe the cap of skins and seeds that forms on the top of the tank exposing the cap to the ethanol of fermentation

  12. Pumping Over Hose Sprinkler Cap Pump Wine Racking valve

  13. Extraction of Skin Components Max A B [cmpd] Time

  14. Extraction Affected By: • pH • Temperature • Length of time • Maceration • Ethanol concentration • Total amount in skin cells • Enzyme treatments • SO2

  15. Techniques for manipulation of red must composition • Maceration

  16. Maceration • Pre-fermentation maceration • Temperature • Length of time • Number of pump overs/day • Type of pump over • Spray • Punch down • Rotary tank • Ethanol at time of pressing

  17. Maceration • Post-fermentation maceration • As CO2 bubbles, which provided buoyancy to the cap, dissipate, the cap sinks • Maceration can continue for one to four weeks after cap settling • Also aging on yeast lees

  18. Thermoflash maceration • New technique for rapid heating/cooling of must • Use vacuum for rapid cooling • Combination destroys plant cell walls and permeability barrier • Greatly increases extraction

  19. Techniques for manipulation of red must composition • Maceration • Temperature of Fermentation

  20. Techniques for manipulation of red must composition • Maceration • Temperature of Fermentation • Pressing Conditions

  21. Techniques for manipulation of red must composition • Maceration • Temperature of Fermentation • Pressing Conditions • Thermovinification

  22. Thermovinification • Hold must at high temperature (60-80ºC) for a short (seconds) period of time • Grapes: Steam treatment so surface reaches 75ºC, pulp no more than 30ºC.

  23. Consequences of Thermovinification • Heat denaturation of enzymes (PPO) • Increase color extraction • Increase Phenolics • Increase stability of “purple dimer” • Alters microbial flora • Easier to press • Characteristic flavor changes

  24. Flavor Changes of Thermovinification • Fruit characters intense but less complex • Increase vegginess (may be too intense once fruit disappears) • Hydrolyze terpene glycosides to free terpenes • Aging/Chemical reactions occur

  25. Red Wine Color • Due to anthocyanins • Anthocyanins can be glycosylated • Anthocyanins can be acylated or have another type of molecule attached to first sugar • Acylated pigments less sensitive to bleaching and oxidative loss • Extracted at different rates

  26. Anthocyanins R OH + HO O R’ O-Gluc OH

  27. Anthocyanins Delphinidin: R=OH; R’=OH Cyanidin: R=OH; R’=H Peonidin: R=OCH3; R’=H Malvidin: R=OCH3; R’=OCH3 Petunidin: R=OCH3; R’=OH Pelargonidin: R=H; R’=H

  28. Factors Affecting Must Color • Variety • SO2: flavene sulfonate is colorless • pH • Protonated form = red • Quinoidal base = blue • H-bonding between protonated form and quinoidal base = purple • Co-pigmentation

  29. Anthocyanin Structures R R OH OH + HO O O H+ O R R O-Gluc O-Gluc OH OH Quinoidal base Flavylium cation R R H2 O H+ OH OH OH OH O HO O HO R R O-Gluc O-Gluc OH OH Chalcone Carbonyl pseudo-base

  30. Effect of pH on Anthocyanin Structure 100 % of Total 50 0 1 2 3 4 5 6 pH

  31. SO2: Bleaching of Anthocyanins R OH + HO O R SO2 O-Gluc OH Flavene Sulfonate R Flavylium cation OH O HO R O-Gluc H SO3 H OH

  32. Anthocyanin Structures R Hydrogen bonding occurs between the Quinoidal base and Flavylium cation stabilizing the purple color OH + HO O R O-Gluc R OH O H H O O R O-Gluc OH

  33. Co-Pigmentation Refers to the observation that color does not appear to be a linear factor upon dilution – absorbance decreases faster than can be accounted for by simple dilution.

  34. Co-Pigmentation: Lack of Linearity of Absorbance upon Dilution 1.0 Absorbance 0.5 0 1 2 3 Dilution Factor

  35. The remaining aspects of red wine production will be considered in following sections of the course.

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