Not every wine that tastes off is necessarily "bad," but understanding the difference between a wine flaw, a corked wine, and spoilage is essential for every wine enthusiast. Here’s a guide to identifying when a wine has gone bad, what it means for a wine to be corked, and how to recognize the signs.

What does it mean for a wine to be bad?

A wine is considered bad when it no longer tastes as intended, usually due to spoilage or exposure to unfavorable conditions. Here are common reasons wine can go bad:

1. Oxidation:
   When a wine is exposed to too much oxygen, it can lose its vibrant flavors and aromas, tasting flat or sour instead. Oxidized wines often have a brownish hue and aromas reminiscent of overripe apples or sherry (in wines that shouldn’t have those notes).

2. Heat damage ("cooked wine"):
   Excessive heat can ruin a wine’s delicate balance, leading to dull flavors and a stewed fruit taste. This often happens when wine is stored in hot conditions, such as a car trunk or near a heat source.

3. Microbial contamination:
   In some cases, bacteria or wild yeasts can take over the wine, leading to off-putting flavors like vinegar, sweaty socks, or nail polish remover. This is especially common in natural or low-sulfur wines that lack preservatives.

What is corked wine?

Corked wine refers specifically to a flaw caused by a contaminated cork. It’s the result of a chemical compound called TCA (2,4,6-trichloroanisole), which forms when natural cork comes into contact with certain fungi and chlorine-based substances during production. Corked wine isn’t harmful to drink, but it significantly alters the wine’s aroma and taste.

Signs of a corked wine:

• Smell: The most telltale sign is a musty, damp cardboard or wet basement aroma.

• Taste: Corked wine tastes dull, with muted flavors and no fruitiness. It can also have a bitter aftertaste.

• Appearance: Unlike other flaws, corked wine doesn’t typically change in color, so you can’t identify it visually.

Corked wines are relatively rare, affecting an estimated 3-5% of bottles sealed with natural cork.

How can you tell if a wine is bad or flawed?

Here are key signs that indicate a wine might be bad:

1. Unpleasant aromas:

   • Vinegar or nail polish remover: Indicates volatile acidity (too much acetic acid).

   • Rotten eggs or burnt rubber: Suggests sulfur-related faults, often from improper winemaking.

   • Musty or damp smells: Likely cork taint (TCA).

2. Strange appearance:

   • Browning or unusual cloudiness: Can indicate oxidation or microbial activity.

   • Bubbles in still wine: May suggest unwanted secondary fermentation.

3. Off flavors:

   • Sour or sharp taste: Could result from spoilage or improper storage.

   • Lack of fruit or overly bitter notes: Common in corked or heat-damaged wines.

Can bad wine make you sick?

While bad wine can taste unpleasant, it’s unlikely to make you sick. Most wine faults are harmless, though they can ruin the drinking experience. However, wine with microbial contamination may cause minor stomach discomfort.

What to do if your wine is bad or corked

If you suspect your wine is bad or corked:

• Inspect the bottle: Check the cork, seal, and storage conditions. A crumbled or moldy cork could be the culprit.

• Taste carefully: If the wine smells strange but doesn’t taste off, it might still be drinkable. However, corked wine is almost always undrinkable.

• Return it: Many retailers and restaurants will replace or refund a faulty bottle. Don’t hesitate to bring it back.

The swirl perspective

Whether you’re identifying a corked bottle or navigating wine faults, Swirl helps you learn more about wine and make confident choices. Use our app to track and document the wines you have tried.