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New Ideas for Measuring Oxidation

New Ideas for Measuring Oxidation. Andrew L. Waterhouse. Collaborators. Maurizio Ugliano Bruce Currie Stephane Vidal Jean-Baptist Dieval Olav Aagaard Mauri Anderson Alexander Chassy. Wine Oxidation Reactions. Managing Wine Oxidation. Oxygen is consumed Quinone reversal to phenol

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New Ideas for Measuring Oxidation

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  1. New Ideas for Measuring Oxidation Andrew L. Waterhouse

  2. Collaborators • Maurizio Ugliano • Bruce Currie • Stephane Vidal • Jean-Baptist Dieval • Olav Aagaard • Mauri Anderson • Alexander Chassy

  3. Wine Oxidation Reactions

  4. Managing Wine Oxidation • Oxygen is consumed • Quinone reversal to phenol • Limit Fenton oxidation • Quench H2O2 • Reactions of Fenton products • Color development • Measure Oxygen Consumed!

  5. Measure Oxygen Consumed in Bottle? • Oxygen entering bottle • At bottling • From closure • Oxygen transfer through closure • Subtract residual oxygen • Balance: consumed oxygen • How can we measure oxygen entering bottle

  6. Oxygen Measurement in Bottles, etc • Device emits blue flashes • Dots in container luminesce with red light • Rate of decay is related to [O2]

  7. Measuring Oxygen Entering BottleModel Bottle • Diéval JB, Packag. Technol. Sci. 2011; 24: 375–385 • Provides prediction for the same closures!

  8. Oxygen Consumption by Wine • Add oxygen entering bottle • Oxygen at bottling • Oxygen from closure transmission (model bottle) • Subtract current O2 (Nomasense) • Difference is Total Consumed Oxygen, TCO • Oxygen that has been consumed by wine • Apply to an experiment

  9. Interaction of Wine Prep, ClosuresExperiment on Chardonnay • Chardonnay Wines • Oak barrel vs SS barrel • Lees aging vs no lees • Four Closures • Light • Premium • Premium, 4% O2 • Premium, N2 • Accelerated Aging Experiment • High O2 at bottling

  10. Measurements • O2 by Nomasense • Carbonyls by DNPH • Phenolics by HPLC • SO2 by Ripper • others

  11. DO and HSO

  12. TCO Data

  13. Free SO2 Data

  14. Sulfur Dioxide and Oxygen • Theoretical Balanced Reaction • 2 SO2 + O2 → 2 SO3 • Mass ratio, 4 SO2 to O2 • So, with 4/1 ratio of consumption • Balanced reaction • Complete protection from oxidation • Ratio below 4: oxidation of other components

  15. Antioxidant Reactions of SO2

  16. Consumed Free SO2/TCOAt End of Experiment

  17. Different Consumption Ratios • Lees aged wine had higher Consumed SO2/TCO • How can we explain different ratios? • Lees aging increases ratio • WM’s report that lees aging is protective • Lees aged wines had less pyruvic acid

  18. Model Quinone SO2 reaction

  19. Effect of Pyruvic Acid • Decreases the ability of SO2 to reduce quinone • Compromises the antioxidant effect of SO2 • Need to understand which wine components are affecting these reactions • “Weak binders”

  20. Measurement of Free SO2 • Titration with I2 • Appearance of excess I2 after SO2 depleted

  21. Weak SO2 Binding Agents • Pyruvate • Alpha-keto glutaric acid • Galacturonic Acid • Other aldehydes, ketones

  22. Barrel Aging on Lees • Lower level of pyruvic acid! • Yeast lees or bacteria seem to metabolize aldehydes and ketones, reducing them to the alcohol form • Thus, the free SO2 as currently measured, is more available for protective reactions • So, during oxidation, the consumed SO2/TCO ratio is higher

  23. Application of SO2/TCO Ratio • May be predictive of protection by SO2 • Measurement takes time • At least two time points needed • Need time to consume both oxygen and SO2 • Could a titration of SO2 versus SO2/TCO Ratio show what level of SO2 could be protective?

  24. Improved SO2 Measurement • Predictive of reactive SO2 • Quick measurement • Avoids dilution or equilibration effect from titration or other treatment

  25. Summary • TCO in bottle is a key new measurement • Based on consistent closures • Comparison of TCO vs SO2 consumed appears to be useful • Ratio of 4 indicates no oxidation products • Ratio below 2 leads to significant oxidation • Value below 4 needed for development-phenolics • Protection by “free” SO2 is not linear • Interference by carbonyls? • Free SO2 measures need improvement

  26. Major Support • Nomacorc • American Vineyard Foundation

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