Why Do Open Bottles of Wine Go Bad?

There are three key things that impact the flavor and characteristics of wine and other liquids like specialty cooking oils. Each of the factors contribute to making an open bottle of wine go bad over time. The three factors include:

• Temperature. Warm surrounding air temps damages wine
• Direct Sunlight. Harmful UV rays penetrate the clear glass and hurt the wine (as well as warm it up - see previous bullet)
• Exposure to Air. More specifically, exposure to oxygen. Oxygen touching the wine surface causes oxidation

When all three of these factors are in play, the wine flavor can degrade quickly. How quickly the wine goes bad depends on how extreme, and for how long, the wine is subjected to one or all three of these issues!

Here's how each factor affects wine - and more specifically - an open bottle of wine, causing the wine to go bad. You don't have to be a scientist to know what's going on, and you don't have to build an expensive wine cellar to prevent bad things from happening!

Warm Temperatures Hurt Wine

There is no question that warmer temperatures affect - and degrade - wine flavor. This is why wine cellars and wine fridges exist! These are places to store wine that keeps the bottles cool and dry. The best temperature to store bottles of wine is around mid 50 degrees.

But, you need to be careful, as "warm temperatures" in this context can mean anything above 70 degrees. This is the "danger zone", according to Wine Enthusiast and their excellent article "At What Temperature Does Wine Spoil."

If you're the type who ages their wine in the back seat of your car on the way home from the store, you'll also enjoy this Wine Folly article "Your Bottle May Be Suffering From Wine Heat Damage."

What to do? Here's what you can do to keep your open bottle of wine cool. This list is price descending, for those people (like us) on a budget:

• Dig a wine cellar
• Buy a wine fridge
• Put the wine in your current fridge
• Keep it in a relatively cool place (i.e. NOT on the top of your fridge)

Direct Sunlight Hurts Wine

Yep, sunlight hurts, too. Not only does direct sunlight heat the wine (see above for damage due to warm temps), it also exposes the wine to harmful UV rays. Exposure to direct sunlight can begin to break down the wine structure inside the bottle. The result is premature aging - and who wants that in their life?

For more details on why and how sunlight makes wine go bad, check out this article from Vinfolio: "How Much Light is Bad Light When Storing Wine?" 

In the meantime, as someone recommended to me years ago, treat your wine like a shade loving plant. This didn't help me much, I'm afraid, as I seem to be incapable of keeping plants alive either inside or outside my house...

What to do? Keep your bottles away from direct sunlight, and even out of a very bright room. Cool and dark places are best. Note: this applies not just to bottles of wine you are storing, but also that open bottle of wine you just poured a glass from and are only "storing it" until tomorrow. Keep the bottle away from direct sunlight.

Exposure to Oxygen Makes Open Bottles of Wine Go Bad

Have you ever heard the term oxidation? 

• A freshly-cut apple turns brown, a bicycle fender becomes rusty, or a copper penny turns green. What do all of these events have in common? They are all examples of the process known as oxidation.
• Oxidation is defined as the interaction between oxygen molecules and all the different substances they may contact, from metal to living tissue.
• Oxidation can be destructive, such as the rusting of an automobile or the spoiling of fresh fruit.

For wine lovers, the most important instance of oxidization is what happens inside our open bottle(s) of wine!

How an Open Bottle of Wine Goes Bad

What happens to an apple once you cut it or bite in to it? It starts to turn brown due to oxidization. That is what's happening to your wine once you open the bottle. As the oxygen in the air settles on top of the wine inside the bottle, oxidization begins. The wine begins to "turn brown", if you will.

You probably won't notice the affect right away. However, leave the open bottle of wine unprotected over a period of hours or days, and you will absolutely taste the change in flavor that oxidation causes. Over time, your wine will taste like this:

To reduce or even prevent oxidization from happening to our open bottles of wine, we can do several things.

How to Prevent Your Wine From Going Bad

Once you've opened a nice bottle of wine and poured a glass, how do you keep the rest of the bottle tasting fresh for hours, days, or even weeks? Follow these steps:

1. Keep the open bottle of wine in a cool dry place
2. Keep the open bottle of wine in a place that avoids direct sunlight
3. Use an effective wine preservation method to create a barrier that prevents the wine from oxidizing

For more details on how to preserve wine at home, check out our articles on "How to Preserve and Open Bottle of Wine at Home" and "Why Use a Wine Preserver at Home."  

Using a wine preservation system does not have to be complicated, expensive, or gimmicky. A 100% argon preserver does a great job preventing oxidization and will cost you pennies per bottle saved.

Do Specialty Cooking Oils Oxidize?

Yes. The situation above also affects your specialty cooking oils. To retain their desired flavor profile and make them last much longer, use the same techniques described above to help preserve an open bottle of wine. Keep the oil cool, away from sunlight, and add a protective layer to prevent oxidization.