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Winemaking Decisions and Wine Composition: Overview

Winemaking Decisions and Wine Composition: Overview. Linda F. Bisson Department of Viticulture and Enology University of California, Davis. Everything you do has an impact. Juice and Wine Processing. Pre-fermentation Processing Fermentation Management Post-fermentation Processing Aging.

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Winemaking Decisions and Wine Composition: Overview

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  1. Winemaking Decisions and Wine Composition: Overview Linda F. Bisson Department of Viticulture and Enology University of California, Davis

  2. Everything you do has an impact

  3. Juice and Wine Processing • Pre-fermentation Processing • Fermentation Management • Post-fermentation Processing • Aging

  4. Pre-Fermentation Processing • Harvest Decisions • Crushing • Pressing • Temperature of each • Sulfite addition • Inoculation strategy • Microbial bioloads

  5. Juice/Must Treatments • Skin contact • Cold Soak • Clarification • Additions • Adjustments

  6. Skin Contact • Allowing juice to remain in contact with skins and seeds • Increases extraction of material from skins • Increases astringency • May be done at varying temperatures • Will occur during pressing operation

  7. Cold Soak • Cold Soak:holding red must at low temperatures for an extended period of time prior to fermentation to increase extraction of components • Impacts microbial flora

  8. Clarification • Removal of suspended particles in juice • Can facilitate downstream processing • May be removing needed yeast nutrients (over-clarifying)

  9. Juice Clarification • Natural (Gravity) Settling: • Rack Juice from lees: results in loss of volume • Batch and Continuous Drainers • To separate juice from solids • Control size of particles removed • Centrifugation • Can lead to aeration of wine • May strip too many solids

  10. Juice Clarification • Filtration • Juice may be difficult to filter • Flotation • Use of fine suspension of gas (nitrogen) bubbles • Suspended pulp becomes attached to bubbles and floats to surface allowing removal

  11. Juice/Must Additions • Nutrient additions • Direct impacts on microbial growth • Indirect impacts on wine chemistry

  12. Juice/Must Additions • Nutrient additions • Microorganisms

  13. Microorganisms • Yeast: Saccharomyces cerevisiae or Saccharomyces bayanus: No limit on addition, typically no more than 106 cells/mL. • Bacteria: Malolactic bacteria, generally Oenococcusoeni: Also no limit on addition, can be as high as 108 cells/mL

  14. Juice/Must Additions • Nutrient additions • Microorganisms • Enzyme additions

  15. Enzyme Additions • Amylases: breakdown complex polysaccharides • Cellulases: breakdown complex polysaccharides • Pectinase: breakdown pectins • Protease: breakdown of proteins • Glycosidase: release of terpines

  16. Purpose of Enzyme Additions • Increase yield • Facilitate settling • Release flavors • Prevent wine haze from forming later in processing

  17. Juice/Must Additions • Nutrient additions • Microorganisms • Enzyme additions • Inert solids

  18. Inert Solids • Settling aids to increase clarification of juice • Increase solids content to facilitate yeast fermentation

  19. Juice/Must Additions • Nutrient additions • Microorganisms • Enzyme additions • Inert solids • Sulfur dioxide (SO2)

  20. Sulfur Dioxide • Antioxidant: enzymatic • Antimicrobial • Stimulation of yeast • Bleaches red wine color

  21. Juice Additions • Nutrient additions • Microorganisms • Enzyme additions • Inert solids • Sulfur dioxide (SO2) • Dimethyl Dicarbonate (DMDC)

  22. Juice Additions • Nutrient additions • Microorganisms • Enzyme additions • Inert solids • Sulfur dioxide (SO2) • Dimethyl Dicarbonate (DMDC) • Ascorbic Acid: Antioxidant

  23. Juice Additions • Nutrient additions • Microorganisms • Enzyme additions • Inert solids • Sulfur dioxide (SO2) • Dimethyl Dicarbonate (DMDC) • Ascorbic Acid: Antioxidant • Oxygen

  24. Oxygen • Stimulates microorganisms • Required by yeast for optimal ethanol tolerance • Stimulates oxidation reactions so oxidation products can be removed early (does not always work!)

  25. Nutrient additions Microorganisms Enzyme additions Inert solids Sulfur dioxide (SO2) Dimethyl Dicarbonate (DMDC) Ascorbic Acid: Antioxidant Oxygen Water Juice Additions

  26. Acidity Adjustment • Increase acidity • Tartaric and malic acid addition • Ion exchange • Decrease acidity • Calcium carbonate (not below 6 g/L) • Ion Exchange • Alter pH • Ion Exchange

  27. Post-Fermentation Operations: • Clarity • Compositional adjustment • Stability • Style • Packaging

  28. If Everything Has an Impact, How do you decide what to do?

  29. Winery Trials • Needs to be done with your equipment • Needs to be done with your fruit • Needs to be controlled – meaning you can reach a solid conclusion • Needs to be evaluated using your subsequent processing strategy

  30. The Importance of Controls • Minimizing number of impact variables • Isolation of effects • Will dictate what question you are really answering

  31. Today’s Program • Pressing • Pressure and skin contact • Oxygen treatment effects • Pre- and during fermentation • Tannin management

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