There’s White Stuff On My Wine!

Sampling WineI have an overrun one gallon jug of Merlot on its 2nd racking and its got some white moldy looking stuff on top of the wine between the wine and the stopper . Which is a 1 inch gap. What’s up with that? And should I rack it and see what happens or what?Name: Dennis D.
State: PA.
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Hello Dennis,
It could be a mold beginning to forming, but most likely it is a bacterial infection. This can happen if the wine has completed its fermentation and has become still. When an air-lock goes dry or is taken off the glass jug, fresh air can encourage bacteria to grow. Winemaker’s refer to this as flowers.
It sounds like you have a very small amount in the neck of the glass jug. This is not too serious and can easily be overcome. I would go ahead and rack the wine into another sanitized jug.
If the fermentation has already completed, I would not hesitate to add sulfites to the wine: add either a Campden tablet or 1/16 teaspoon of either potassium metabisulfite or sodium metabisulfite. This will easily destroy the bacteria. The wine should be perfectly fine after that, but you will only be able to find out by smelling and tasting the wine.
If the wine is still fermenting then you’ll just have to wait it out. You can siphon the wine into another sanitized gallon glass jug. Siphon from the middle so as to leave both the surface scum and the sediment behind. Once the fermentation does complete, be sure to get the sulfites on the gallon of wine as soon as the fermentation completes.
A blog post you may want to take a look at is There’s White Scum On My Wine. What Should I Do? This goes over in a little more detail what you can do to fix the problem. Another one that my glean some insight is Can You Have Head-Space In Your Secondary Fermenters?
Again, you situation does not sound too serious. My instincts tell me the wine will be just fine, but you’ll have to depend on your own smell and taste to really know.
Happy Winemaking,
Ed Kraus
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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.

2 thoughts on “There’s White Stuff On My Wine!

  1. I have a yellow scum which has stained my primary fermenter after fermentation. Also accumulates on my stirring rod. What is it and how can it be removed?

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