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Oxygen Measurement

Oxygen Measurement. Aerative Pumpovers. Jonathan R. Cave University of California, Davis Viticulture and Enology. Oxygen’s Role in Fermentation. Yeast Metabolism/Utilization of Oxygen Oxygen requirements Lipid synthesis for plasma membrane integrity 1,2

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Oxygen Measurement

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  1. Oxygen Measurement Aerative Pumpovers Jonathan R. Cave University of California, Davis Viticulture and Enology

  2. Oxygen’s Role in Fermentation • Yeast Metabolism/Utilization of Oxygen • Oxygen requirements • Lipid synthesis for plasma membrane integrity 1,2 • Brewing specification – Strictly monitored/controlled • Yield different aroma and flavor product depending upon available oxygen • Molecular Reactionsfor Flavor and Aroma • Iron activation to superoxide • Quinone Activation/Fenton reaction • Peroxide radical – highly reactive • Saturation is 8200 ppb 3

  3. Sensors Clark Sensor Fluorescence Quenching • Optical Sensor • 475 nm Fiber Optic (Blue) • 600 nm Fluorescence (Orange) • Sanitizable/Autoclavable • High chemical tolerances • Physically Divided or Direct • Non-Invasive • No consumption • Polarographic (800 mV) Electrode • Traditional Dip-Probe • Developed by L. C. Clark (1956) • O2 Permeable Membrane • Amperometric Ag/AgCl • Movement - Dip, In-Line Flow • Invasive • Consumes O2 – Negligible

  4. Clark SensorPolarographic Electrode • Requires Flow or Mixing • O2 Diffuses through membrane • 2 diffusion processes (Membrane and Solution) • Membrane < 20µm so that equilibration across membrane is time limiting rather than the reaction • 10-20 seconds equilibration • Stable in under 1 minute

  5. Interferences Clark Fluorescence • Temperature Sensitive (External Compensation) • Acetone, Toluene, Chloroform, Methylene Chloride, Chlorine Gas, Organic Vapor • Temperature Technically (Internal Thermistor) • H2 (g) SO2, H2S • Replenish Electrolyte

  6. Fluorescence Quenching5 • 475 nm Fiber Optic • Excites Fluorescent Dye • FOXY – Hydrophobic Sol-Gel • Pt-porphyrin • Fluorescent Dye in Polymer Matrix • 600 nm Fluorescence • Dynamic Fluorescence Quenching • Collision of O2 with fluorophore causes “non-radiative energy transfer” exciting O2 into triplet state

  7. PreSens Oxygen Sensor Spots 4 Experimental Relevance Winery Applicability • 0.5cm, Physically Divided (Sight Glass) • Flow Rate Independent • pH, CO2, H2S, SO2, Ionic Species • Chemical Tolerance • NaOH, H2O2, HCl • CIP - autoclave, steam • Linear Range 1-1800 ppb • Accuracy ± 1 ppb • LOD: 1 ppb • Minimal Cross Sensitivity • Yes: Acetone, Chlorine Gas • No: CO2, H2S, SO2 • Compatible with Ethanol

  8. Oxygen Management in Winery OperationsJonathan Cave, Nick Gislason, Andrew Waterhouse • Goal • Comprehensive model of oxygen availability, necessity, benefit, and detriment from vine to glass Crush Cap Manipulation Racking Pressing Barreling Down Bottling

  9. Winery Operations Aerative Pumpovers Splash Racking, Rack and Return, Delestage-ish • High Anticipated Oxygen Solvation • Desired Oxygen Uptake • Early in Fermentation - Low EtOH/High Sugar • SO2 - Oxygen scavenger and Interaction Inhibitor?

  10. Experimental Design • Observed 29 Pumpovers • 23 Aerative • 6 Closed Controls • Within first 3 days of fermentation • Pumpovers by experienced cellar staff • Well practiced technique • Not harvest interns • No alteration by experimenters • No interference in the production process • Required Observational Treatments

  11. Oxygen Sensor Spots– Paired Values

  12. Parameters • Drop – Distance from Screen to Wine • Splash – Radius and Walls • Flow Rate – From Racking Arm • Flow Type – Screen interaction • Two Conditions • Drop – Large/Small • 10” vs. 4” • Splash – Intense/Mild • Spread and Arcing • Flow Rate – Fast/Slow • Flow Type – Turbulent/Laminar

  13. Oxygen Solvation/Assimilation Data • Range: 70 - 2300 ppb • Closed PO Control – 0 ppb • Drop – Most Relevant • STDEV of lower [O2] too high • CV >75%

  14. Data Analysis • Non-Separable Treatments • Coincident Treatments • Interdependence of Rate, Type and Splash • Cannot discern combination of effects or sole influence • Drop is the only separable Parameter • This is not to say they are irrelevant – need more data

  15. Variability • Experimental Variation of Large Drop • We should expect no significant difference • Enough variability that operations are unpredictable • Distinct groups within the single treatment • Combination of effects may attribute to variation • Refinement of current technique is necessary

  16. Conclusions and Future Work • Variability is immense • Multiple control parameters influence oxygen exposure and solvation • Despite exceptional technique by experienced cellar staff, best control possible, oxygen assimilation into wine by aerative pump over, a commonly employed technique, is inconsistent and capricious. • Technique must be improved • Oxygen levels throughout production are largely uninvestigated • Industry Survey to determine variability • Refinement capability or Operational paradigm shift • Experimentation under strict experimental controls during all winery operations at UC Davis winery • Future collaborations are needed

  17. Acknowledgments • Nick Gislason • Andrew Waterhouse • References • 1.) Andreasen, A. A., & Stier, T. J. B. 1953. Anaerobic nutrition of Saccharomyces cerevisiae. I. Ergosterol requirement for growth in a defined medium. Journal of Cellular and Comparative Physiology, 41, 23–36 • 2.) Andreasen, A. A., & Stier, T. J. B. 1954. Anaerobic nutrition of Saccharomyces cerevisiae. II. Unsaturated fatty acid requirement for growth in a defined medium. Journal of Cellular and Comparative Physiology, 43, 71–281 • 3.) Ough, C.S. and M.A. Amerine. 1988. Methods for analysis of musts and wines, 2nd, Wiley, New York. • 4.) Huber, C., T.-A. Nguyen, C. Krause, H. Humele and A. Stangelmayer. 2006. Oxygen ingress measurement into pet bottles using optical-chemical sensor technology. BrewingScience 5-15. • 5.) http://www.oceanoptics.com/Products/sensortheory.asp

  18. Supplemental Materials

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