1 / 14

Negative Impacts of Oxygen in Wine

Negative Impacts of Oxygen in Wine. Linda F. Bisson Department of Viticulture and Enology University of California, Davis. When Is It Over-Oxygenation?. Defects associated with excessive oxygen exposure appear Dependent upon wine composition. Issues With Over-Oxygenation. Chemical

Download Presentation

Negative Impacts of Oxygen in Wine

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Negative Impacts of Oxygen in Wine Linda F. Bisson Department of Viticulture and Enology University of California, Davis

  2. When Is It Over-Oxygenation? • Defects associated with excessive oxygen exposure appear • Dependent upon wine composition

  3. Issues With Over-Oxygenation • Chemical • Enzymatic • Microbial

  4. ChemicalIssues • Alcohols become aldehydes • Organic acids become keto acids • Reaction with thiols and loss of • varietal character • Off-Color formation • Extensive loss of color and wine becomes sherry-like

  5. Aldehydes in Wine • Aldehydes • Acetaldehyde from oxidation of Ethanol • Fusel Aldehydes from oxidation of Fusel Alcohols • Benzaldehyde from oxidation of Benzyl Alcohol • Formed chemically from grape/yeast precursors or directly synthesized by microbes • Perception can be enhanced by acetic acid

  6. Acetaldehyde • Low concentrations: apple, unripe apple • Higher concentrations: oxidized apple, nutty, pungent, chemical • Appearance indicates ethanol is being oxidized and wine should be protected from further oxygen exposure

  7. Fusel Aldehydes • Fusel alcohols (oils) are made during amino acid degradation • Fusel alcohols can be reoxidized to aldehydes during aging • Recent experiments suggest fusel aldehydes may be important “impact” compounds in wine

  8. Fusel Aldehydes • Isobutyraldehyde: banana, acrid, pungent • Isovaleraldehyde: nutty, fruity, cocoa, pungent, acrid • 2-Methyl butyraldehyde: aldehydic, berry, cocoa, musty

  9. Benzaldehyde • Characteristic of oxidized wines • Bitter cherry at low concentrations • Chemical taint at higher concentrations • Can be made microbially

  10. Off-Colors • Browning • Pinking • ‘Going Orange’

  11. Enzymatic Issues • Laccase

  12. Microbial Issues • Spoilage Organisms • Acetic Acid Bacteria • Brettanomyces • Staphylococcus • Flor Yeast

  13. Staphylococcuspasteuri • Isolated from MOX wine • Normal grape flora resident • Obligate aerobe – sign of beyond excessive oxygen exposure

  14. Oxygen Treatments of Wine • Need to know the amount of exposure and its consequences and impact on wine, which will vary by the wine • Monitor for signs of excessive oxygen • If push wine to edge of oxygen consumption, will shorten shelf life

More Related