ask dr. vinny

Hello there! I'm Dr. Vinifera, or "Vinny" for short. Ask me your toughest wine questions, from the technical aspects of winemaking to the fine points of etiquette. I hope you find my answers educational and even amusing. Looking for a particular answer? Check my archive and my FAQs. You can also follow me on Twitter: @AskDrVinny.


Dear Dr. Vinny,

If you leave a wine for one or two days out in the open and it starts to taste bad, does the alcohol content increase or decrease? And by how much?

—Georgia, Ohio

Dear Georgia,

Even though a wine will probably taste different if it’s been open for a couple days—including possibly the alcohol sticking out a bit more—that doesn’t mean the percent of alcohol by volume will change. Same thing with changing a wine’s temperature or even aging a wine—alcohol percentages don’t change. Perception is one thing, but the chemistry of wine is another.

A wine’s alcohol content is determined during fermentation, when the sugar in the grapes is converted to alcohol. Sure, if you opened a bottle of wine, poured the entire thing into a shallow pan pointed a fan at it and let the surface of the wine evaporate for a couple of days, you might be able to calculate a difference—the alcohol would start to evaporate more quickly than the wine’s water content. But I’m guessing that once you open a bottle of wine, you keep the wine in its bottle, where there is much less surface area, and much less evaporation occurring, and any changes zero to negligible.

You will notice your perception of wine will probably change as a wine is open for minutes, hours and even days if you want to experiment.

A much more fun science experiment would be to put red wine in a pan and start to heat it up, perhaps even setting it aflame to increase the evaporation, reduce it a little further, and then you have a terrific red-wine reduction sauce to braise short ribs in.

—Dr. Vinny


Do you have a question for Dr. Vinny? Ask it here...

Wine Basics

We break down the basics—how to taste, serve, store and more. Plus:
» Maps of major wine regions
» Grape variety characteristics

How-to Videos

Learn to taste wine like a pro, pull a cork with flair, get great wine service in a restaurant and more

Wine Spectator School: All courses are FREE for WineSpectator.com Members

Learn from the experts and get the most out of each sip. Take one of our online courses or take them all—from the ABCs of Tasting to in-depth seminars on Food Pairing, California Cabernet, Bordeaux, Tuscany, Sensory Evaluation and more.

Browse our course catalog
Check out the professional wine sales and service courses
Learn Wine Forum: Got questions? Get answers

MEMBER LOGIN

= members only

Keep me logged in      Forgot Password?

Free Email Newsletters

Sips & Tips | Wine & Healthy Living
Video Theater | Collecting & Auctions

» View samples
» Or sign up now!
» Manage my newsletter preferences

Classifieds

The marketplace for all your wine needs, including:

Wine Storage | Wine Clubs
Dining & Travel | Wine Auctions
Wine Shops | Wine Accessories