A friend gave me a bottle of homemade wine and the top of the cork is green and fuzzy. Is it still safe to drink?
Having mold on top of the wine cork of your friend’s homemade wine has little to do with what’s inside the wine bottle. In other words, the mold did not come from the wine but from the environment outside the wine bottle. It also has nothing to do with the fact that the wine was homemade. It’s not unusual to cut the neck capsule away from a commercially made wine only to find mold underneath.
Mold is everywhere. Invisible to the naked eye, it floats through the air waiting for a place to land and grow. This is why it’s just about impossible to keep fresh strawberries for more than a few days. A single mold spore or two has little effect on anything, but give them nourishment — such as fresh strawberries — and you will see a handful of mold spore grow into a healthy, thriving colony — one that is visible.
This is why your friends homemade wine has mold on top of the wine cork. What little mold that was in the air found its way to the wine bottles and was able to grow on the cork. The nourishment, in this case, is coming from wine slowly seeping through the cork.
Wine corks are meant to stay moist. The moisture keeps them expanded and sealed tight against the inside barrel of the bottle’s neck. Most of the time the cork will seal tight enough to stop the wine from seeping all the way through, but there are many times when wine will slowly wick itself through the entire cork. It’s never in great amounts, for no one wants to waste wine, but it does happen.
After the wine makes its way to the end of the cork, it’s only a matter of time before mold will find it and have a feast on it.
I’m sure you’re wondering what you should do at this point. You’ll be happy to know that the only additional step required is that you take a clean, wet rag and wipe the mold clean from the wine bottle. Once you have done this, you can simply decant the wine as you normally would.
So now you know why there is mold on top of the wine cork. It has absolutely nothing to do with what’s inside the bottle. The mold cannot get to it, it can only grow on the outside.
Happy Wine Drinking,
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.