Why is oxidation bad for wine?

Ask Dr Vinny

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.

Dear Dr. Vinny,

Why is oxidation bad for wine?

—Mikayla, Victoria, Australia

Dear Mikayla,

Whenever I write about oxidation (and aeration), I like to bring up apples. You know how if you bite into an apple and set it aside, the apple will start to turn brown and then take on a nutty flavor? It’s because once you’ve broken the skin of the apple and exposed its flesh to oxygen, it starts to react with the oxygen in the air.

Same with wine. A wine can become oxidized if it’s exposed to too much oxygen while it’s being made, or if too much oxygen gets into the bottle because of a faulty closure. You might have firsthand experience with oxidation if you leave wine in your wineglass overnight and then take a sip, or revisit a bottle that’s been open for a week. The wine’s flavors and aromas will flatten, and those nutty, Sherry-like notes replace the fresh flavors the wine had. Oxidation will also change a wine’s color to brown and brick tones. What is chemically happening is that the wine’s phenols are susceptible to combining with oxygen, and the wine’s ethanol starts to break down and shift into other compounds, like acetaldehyde.

The ill effects of oxidation take hours if not days to show themselves, however. Sweet wines, wines with higher acidity, and more tannic wines tend to have more resistance to oxidation, but after a while, all wines will suffer from too much oxygen.

—Dr. Vinny

Wine Flaws Ask Dr. Vinny

More In Dr. Vinny

What does it mean when a tasting note refers to the “midpalate”? How do you experience it?

Wine Spectator's expert Dr. Vinny explains how—and when—the midpalate is experienced.

Nov 23, 2020

Is my home wine cellar supposed to smell like wine?

Wine Spectator's expert Dr. Vinny explains possible sources of a wine aroma in a bottle …

Nov 16, 2020

What do you call white wines that have a citrusy, fizzy sensation?

Wine Spectator's expert Dr. Vinny explains the difference between acidity and effervescence.

Nov 13, 2020

Should I be concerned about wine freezing in my car if it’s below freezing outside?

Wine Spectator's expert Dr. Vinny answers questions about freezing wine.

Nov 11, 2020

Do you recommend any wine clubs? Are they good holiday gifts for wine lovers?

Wine Spectator's expert Dr. Vinny offers tips for choosing a wine club.

Nov 9, 2020

Could smoke taint in wine be removed by reverse osmosis?

Wine Spectator's expert Dr. Vinny explains how reverse osmosis is used as a tool for …

Nov 6, 2020