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

Is it OK to brush my teeth before tasting wine? Does toothpaste change the way wine tastes?

Wine Spectator's resident wine expert Dr. Vinny explains why brushing your teeth and wine …

Sep 26, 2022

What’s the difference between Hermitage and Ermitage? Are they the same wine?

Wine Spectator's expert Dr. Vinny explains what the H is going on with Hermitage vs. …

Sep 19, 2022

When traveling, are any wines more or less susceptible to bottle shock than others?

Wine Spectator's expert Dr. Vinny explains the phenomenon of "bottle shock" and how to …

Sep 12, 2022

What’s the best way to remove a crumbly wine cork? I’ve tried everything!

Wine Spectator's expert Dr. Vinny offers tips for extracting crumbly corks, and how to …

Sep 7, 2022

What’s the difference between Petite Sirah and Syrah?

Wine Spectator's expert Dr. Vinny explains that Syrah and Petite Sirah have quite a bit in …

Aug 29, 2022

I have about 50 bottles of wine. Should I buy a wine fridge?

Wine Spectator's expert Dr. Vinny offers advice for when to upgrade your wine storage at …

Aug 22, 2022