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Winery Microbial Analyses: Practical Aspects

Winery Microbial Analyses: Practical Aspects. Linda F. Bisson Department of Viticulture and Enology University of California, Davis. Presentation Outline. Brief overview of wine microbiology Management of Microorganisms Practical Aspects: What to monitor How to monitor When to monitor

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Winery Microbial Analyses: Practical Aspects

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  1. Winery Microbial Analyses: Practical Aspects Linda F. Bisson Department of Viticulture and Enology University of California, Davis

  2. Presentation Outline • Brief overview of wine microbiology • Management of Microorganisms • Practical Aspects: • What to monitor • How to monitor • When to monitor • Where to monitor • Who should monitor

  3. Brief Overview of Wine Microbiology • Types of Organisms • Sources of Organisms • Management of Organisms

  4. Types of Organisms • By Taxonomic Classification • Beneficial Versus Spoilage

  5. Taxonomic Classification • Bacteria • Yeast • Molds

  6. Sources of Organisms • Grape • Vineyard • Vineyard Equipment • Transportation Equipment • Winery Equipment • Winery Surfaces • Inoculations

  7. Management of Organisms

  8. Management of Organisms Requires: • Knowing what organisms are present • Knowing when organisms are beneficial, benign or detrimental to quality • Knowing how to stimulate or inhibit specific organisms or classes of organisms and their metabolic activities • Knowing what to monitor and when

  9. Management of Organisms Requires: Knowing what you are trying to accomplish

  10. Detecting the Organisms Present • Microscopy • Plating • Molecular Identification • Sequence-based • Species/Genus/Strain • Specific gene • Surface antigen-based

  11. Detecting the Organisms Present • Microscopy • Organisms “look the same” • Useful if important to distinguish broad classes • Bacteria versus yeast • Apiculate versus non-apiculate yeast

  12. Detecting the Organisms Present • Plating • Can use differential media • Is always a selection • Requires microbial lab capabilities

  13. Detecting the Organisms Present • Molecular Identification • Can require previous knowledge of the sequence of the organism • Some threats may be missed • Some threats may be exaggerated

  14. Is the Organism: Beneficial, Benign or Detrimental?

  15. Is the Organism: Beneficial, Benign or Detrimental? It depends . . .

  16. Is the Organism: Beneficial, Benign or Detrimental? • Organisms conducting a desired process are beneficial • If they cause no harm their presence is benign • If they are active at the wrong time they are detrimental • Different organisms may be in these categories • The same organism can fall into each of these categories

  17. CASE STUDY: Saccharomyces • Beneficial: • Agent of fermentation • Positive impacts on wine aroma • Benign: • Present and viable but inactive • Detrimental: • Capable of re-fermentation post-bottling: are there residual sugar/nutrients? • Spoilage character formation

  18. Management to Stimulate • Create and sustain permissive conditions • Nutritionally complete • Physiochemical Environment • pH • Temperature • Absence of competition • Absence of inhibitors

  19. Management to Inhibit • Create and sustain non-permissive conditions • Depletion of nutrients • Non-permissive temperature or pH • Presence of microbially- derived inhibitors • Sanitation • Addition of inhibitors • Sulfite • Velcorin (DMDC) • Heat treatments/filtration/centrifugation of juice to remove organisms

  20. Management to Inhibit • Know the difference between simple inhibition and cell death (“-static” versus “-cidal”) • Be able to monitor effectiveness of treatment • Be careful not to re-infect • May have to happen in the vineyard, not just winery

  21. Practical Aspects: • What to monitor? • How to monitor? • When to monitor? • Where to monitor? • Who should do monitoring?

  22. What to monitor? • Presence • Viability • Types of activity • Growth • Off-character formation • Enabling of downstream microbial activity • Effectiveness of treatment: sanitation or inhibition

  23. How to monitor? • Do you have a microscope and can you use it? • Do you know what the microbes look like? • Are you able to out-source monitoring? • Do you have in-house capability for: • Microbial identification via plating • Microbial identification via molecular methods • Chemical analyses to follow metabolic activities • Ability to assess viability?

  24. When to monitor? • Ideally throughout the process • Before and after any manipulation • Nutrient addition • Oxygen exposure • Transfers to new cooperage • During aging • Before and after bottling

  25. Where to monitor? • Routine monitoring • Fermentations • Winery surfaces following sanitation treatments • Know hazard points and monitor

  26. Who should monitor? • Monitoring should be done by someone who can make sound judgment calls

  27. Best Practices • Monitor often by nose – this is how you will first spot a problem • Any “funkiness” should be investigated • You will know when it smells off • Even if off-smell usually goes away still check it out each time • Monitor fermentations on a regular basis under the microscope • Know your juice chemistry • Do you need to add nutrients? • Is your pH inhibitory to some organisms? • If you have a problem, seek help if you are unsure of the source and solution

  28. Questions?

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