Written by: Tim Edison

Updated on: November 16, 2022

How to Tell if Wine is Corked [6 Tell-Tale Signs]

wine bottle and cork

Most of us have probably come across the term "corked wine," but what does it really mean?

And more importantly, how do we detect corked wine? Is there a specific taste or smell of corked wine?

We explain exactly what corked wine is and how to detect it in today's wine guide.


What is Corked Wine?

Ok, first we need to dispel a little myth about corked wine...

Corked wine has nothing to do with little bits of cork floating around in your wine.

Yes, this is annoying but it doesn't ruin your wine like one that has been 'corked'.

Corked wine is a term used for wine that is contaminated with cork taint.

Cork taint is caused by the presence of a chemical compound known as 2, 4, 6 -trichloroanisole.

More commonly known as TCA, this chemical compound is formed when natural microorganisms or fungi found in cork (remember cork is a natural substance) react with phenolic compounds in wine (like tannin) and chlorine.

What Causes Corked Wine?

Corked Wine (TCA) = Cork fungi + Phenolic compounds + Chlorine

You may be wondering how chlorine comes into contact with the cork? That was my first question anyway.

When making your own wine, you're always told not to use chlorine based sanitation products and it's certainly a big no no in the industry.

It's been like this since the early 90s when it was realized that cork taint was caused by chlorine.

Trace amounts of chlorine may exist in the cork for a couple of reasons:

  1. 1
    Due to the use of particular plant fungicides (remember cork comes from trees)
  2. 2
    Due to certain bleaches used in sanitation (it can still happen)


Why is Corked Wine Bad?

While drinking corked wine may not be harmful to your health, it can ruin the entire wine drinking experience.

Corked wine is simply unpleasant.

You'll probably notice first by the way it smells.

Instead of floral and fruity aromas you'll be presented with smells like:

  • A funky, moldy odor
  • Wet cardboard
  • A wet dog smell
  • Musty odors

If the smell of the wine doesn't hit you then the lack of flavor might. The flavor profile will be lacking and it will just taste boring.

Cork taint dulls the fruit in a wine, renders it lacklustre and cuts the finish. Some people actually find the taste astringent.  

Cork taint is more obvious to wine drinkers that are more sensitive to flavor. The degree to which a cork is tainted will also make the objectionable smell more noticeable.


Related: Wine has as many as four sensory characteristics. Can you tell what they are?


How Common is Corked Wine?

Estimates suggest that between 2-5% of all wine is corked.

That means at worst 1 in 20 bottles you open is actually ruined and doesn't taste as it should. At best only 1 in 50 are corked.

Still, that's more than enough wine going to waste right!?


Why is Wine Sealed with Corks Then?

Corks became popular when uniform sized glass bottles started gaining popularity. This was thought to have happened way back in late 1600. It took a while longer to develop effective corkscrews though!

Corks restrict harmful oxygen from entering the bottle and aging wine prematurely (wine oxidation can ruin wine).

However, they don't completely restrict air from entering the bottle. A good cork will allow something like 1 milligram of oxygen to enter the bottle in a year. This little bit of air is important to help remove some sulfites. It also helps to develop secondary aromas.

Cork is made from a sponge-like matter found in oak trees, also called Quercus Suber. Cork oak trees are typically found and grown in Portugal.

It found its way in wine bottles way back in the late 1600s when people invented glass bottles with almost the same shape and design.


How to Identify a Corked Wine

If you drink a lot of wine, it shouldn't be too hard to notice when cork taint is having an effect.

These are the tell-tale signs:


1. Does it Use a Traditional Cork?

Sorry, for the really obvious start but it's an important one!

Traditional wine corks are not the only types of stoppers used these days. Synthetic corks, crown caps and screw caps are all common these days.

Traditional cork is the only type of bottle top you'll get TCA cork taint with. If it's not real cork it's not real cork taint!

Drinking wine


2. A Funky Odor

Pay attention to the smell coming out of the bottle as soon as you open it.

If the cork is tainted the smell will not be anything close to what you would expect from a wine bottle.

Instead of fruity and floral aromas you will be presented with a scent similar to mold. Something damp smelling like mushrooms, a wet cardboard box, or even a wet dog! The corked wine smell is very distinctive.


3. Where's the Flavor?

If smelling the wine has still left you undecided then go ahead and take a sip.

Remember, corked wine might not smell or taste great but it's not dangerous to drink.

If the wine was exposed to very small amounts of TCA, it might be challenging to determine for sure if the wine is corked or not by merely smelling it.

The corked wine flavor is flat and boring, and lacking fruitiness. Others describe the taste to be bitter or astringent.

Remember, a corked wine has been spoiled but it will taste differently to one which has been spoiled by heat, for example.


4. Compare Tasting Notes

If you're still undecided on the state of your wine then compare your tasting experience with the tasting notes of the winery.

If there aren't any tasting notes on the bottle then look it up online and find some reviews. Can you relate to other people's experiences?

If you're sharing the bottle with a friend do they have the same lacklustre experience?


5. Double Check!

It can't hurt to reset your nose and your palate and taste again just to be sure.

To reset your sense of smell just simply take a sniff of your forearm (yes, you heard us right!). Just be sure that you don't have any strong smelling lotions on.

To reset your sense of taste, water is a great palate cleanser. Some plain bread does wonders to neutralize any lingering flavors too.

Now after reseting your nostrils and taste buds, go back and smell and taste the wine.

Do you have the same problems? 


6. Don’t Confuse Corked Wine With Other Wine Issues

There are various other problems that can negatively affect the taste of wine.

Unplanned secondary fermentations, excessive exposure to sunlight, and oxidation are just some of the issues facing wine.

Oxidized wine which has been exposed to air for some time and can lead to flat, lifeless wine. White wine could also appear brownish or dull yellow.

Maderization is the process that involves overheating or over-oxidizing wine (probably during transportation). 

This kind of wine has a taste reminiscent of candied fruits or almonds, and the cork may be slightly pushed out of the bottle. This is as a result of the expansion that may occur when the wine gets too warm.

Another big possibility in winemaking is re-fermentation. As much as wine is the final product of fermentation, if the yeast isn't inhibited from further activation (using potassium sorbate) it can sometimes restart the fermentation process after bottling. This can create a fizzy taste and even push the cork upwards.


What To Do Next if You Buy a Corked Bottle

There's only one option really and that's to return the bottle.

You're unlikely to meet any resistance from a shop owner, wine merchant, bartender or sommelier.

Bring both the wine and the cork if possible.

There actually used to be a remedy for corked wine that involved something called Saran Wrap. Dr. Andrew Waterhouse discovered that Saran Wrap would absorb the pesky TCA compound from the wine and dramatically improve the aroma and taste. This effectively reversed the damage done by the cork taint.

However, this awesome trick no longer works.

Part of the reason Saran Wrap could perform this feat was because it contained polyvinylidene chloride (PVDC). It was this polymer that 'pulled' the TCA compound from the wine. 

Saran has since changed from PVDC to polyethylene due to environmental and cost concerns.


Conclusion

Unfortunately, cork taint is just an unavoidable reality of wine drinking.

It's something everyone will experience at some point, knowingly or not!

Theres nothing you can do about it apart from be aware of it and keep you purchase receipts!

When I first learned about it it made me wonder about all those bottles I had drank unaware and not enjoyed.

Did I not enjoy those wines because they were just not good wines or did I not enjoy them because they were dull and lifeless, spoiled by TCA?


Have you ever had corked wine? What was the tell-tale sign for you?


About the Author Tim Edison


Tim started Wine Turtle way back in 2015.
These days he contributes to Wine Turtle (and other renowned wine publications) while continuing his wine education.
Tim's wine of the month is the Coates & Seely Reserve Brut NV (from Hampshire, England).

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