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Introduction to Oxidation in Wine

Introduction to Oxidation in Wine. Andrew L. Waterhouse Department of Viticulture & Enology University of California, Davis. Oxidation Avoidance. Traditional limit to wine preservation Current technology can exclude oxygen Wine oxidation - a fault?. Manage Wine Oxidation.

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Introduction to Oxidation in Wine

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  1. Introduction to Oxidation in Wine Andrew L. Waterhouse Department of Viticulture & Enology University of California, Davis

  2. Oxidation Avoidance • Traditional limit to wine preservation • Current technology can exclude oxygen • Wine oxidation - a fault?

  3. Manage Wine Oxidation • At crush / press • Anaerobic press to hyperoxidation • Fermentation • Add oxygen for yeast, reductive aromas • Post fermentation/s • Micro-ox, barrels, racking • In bottle • Affects flavor development

  4. Oxygen Measurement • Standard meter • Limit of Detection ~0.5 ppm • Orbisphere or other Clark electrode • LOD ~2 ppb • Nomasense, Mocon, others • Oxydots, fiber optic measure-contact not needed! 10 ppb • Temperature sensitive!

  5. Antioxidants • SO2 • Ascorbic acid • Glutathione

  6. Oxygen reacts with phenols to yield quinone and hydrogen peroxide Hydrogen peroxide oxidizes ethanol to acetaldehyde Wine Oxidation Chemistry

  7. Known Oxidation Products • Quinones • Thiol adducts • Coupling Products • Aldehydes • Acetaldehyde • Glyoxylic Acid • (Tartaric Acid product) • Flavonoid coupling

  8. Oxidative Changes in Wine • Formation of quinones from catechols • React with thiols, SO2, ascorbate, phenolics • Fenton oxidation of alcohols • Formation of aldehydes • Reactions of all other substances

  9. Oxygen Pathway in Wine

  10. Sulfur Dioxide and Oxygen • Sulfite is the sink for oxidation • O2 + 2 SO2 2 SO3 • 1 mg of O2 will consume 4 mg SO2 • SO3 + H2O H2SO4

  11. Generation of quinone and hydrogen peroxide from dioxygen Polyphenols are Pro-oxidants

  12. Nikolantonaki , ACA 660: 102 (10) Blanchard, AJEV 55:115 (04) Catechin + 3-Mercaptohexanol

  13. Catechin dimer in model juice • Poupard, J Chrom A, 1179: 161 (08)

  14. Quinone Options

  15. Oxygen Pathway in Wine

  16. Peroxide Competition

  17. Wine Minor Components

  18. Pyruvic Observed in wine Reacts with anthocyanins to make wine pigments Glyoxylic Observed in wine Condenses with flavan-3-ols Oxidation of Wine Acids (Alcohols) to Carbonyls

  19. “D-ring” formation by acetaldehyde and pyruvate Aldehyde Pigment Reactions

  20. Alcohol Oxidations with ∙OH • Aldehydes known oxidation products

  21. Wine Oxidation • Aroma and color changes • Can be managed • A few key steps need better understanding • Many current investigations • State of the art and practice today

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